Umm, that explanation doesn't answer the question at all, since Jadeite made his appearence in the sky over the city hours before the Senshi went to confront him.
Although, from my recollection, the airport was deserted of civilians and swarming with police officers (knocked unconscious and later mind-controlled), which would sort of explain what the city was doing. Doesn't give any explanation for what Ranma, Ryouga, Akane, Kunou, Kodachi, Ukyou, Shampoo, Cologne, Mousse, Happousai, Mikado, Azusa, Mariko, Sentarou, Satsuki, Hayato, Konatsu, Hinako, Soun, Genma, et al are doing, though.
And as far as your zoning concerns go, Necrotoid, I must ask the question: "Who, precisely, enforces this zoning?" Ranma martial artists are effectively above the law; they do whatever they want and the law conforms to them. This is seen in many ways in the series, and it's also notable that when a martial artist or monster makes trouble, the legitimate authorities (like the police) go to martial artists to solve the problem (like Soun Tendo). So too, can Ranma wear whatever uniform he wants at school, fight with the teachers, have a non-standard haircut and take off whenever he feels like it; Kunou gets the same priviliges, and martial artists can cheat outrageously at sporting events without repurcussions. Who's going to tell Ryuu Kumon he can't build his new dojo whereever the hell he wants? The Chinese Communist government stays silent when two giant monsters, one throwing lightning and fireballs, fight each other over Shanghai; neither they nor the Japanese SDF have a military response to mountains getting destroyed in the course of battles by the gods that walk among men... you think some random Japanese cop is going to push a guy around who could punch down a building? And these people aren't that rare - there's apparently one or two in every high school, and nobody's that shocked over the feats they can do. That says nothing, of course, about the fact that in Ranma 1/2 Shinto is undeniably real, because the gods can show up and fuck around with you if you piss them off. Magic is real, and there's people out there with power that more than rivals nuclear weapons. You want to fight a martial artist? Don't get a gun, you silly norm - they'll hit you six times before you pull the trigger. Buy one of our battlesuits that feeds off their chi and makes you an ubermensch too! But be careful, that technology is unstable!
If the world's technology and governance is similar to our own (and every indication is that it is, with a few exceptions), then law and order and government by non-superpowered people exists only at the sufference of the demigods who stride the earth fighting their private little battles and pursuing their personal goals. And that's JUST Ranma 1/2. When you add more things to the mix, regular folks get inevitably more and more impotent. It's the inevitable consequence of a pyramid - the higher the spire reaches, the more bricks must be at the bottom and the deeper they're pushed into the mud.
(Edit: Oh, and it's worse than that. Shinto isn't the only religion with real gods - there is a god Asura, and that god has real power. The Asuras, demon/Hades-analogues from Hindusim, came from pre-Hindu myths... if that means all the Hindu deities exist... holy crap. If all the Taoist ones do too... holy CRAP. And then who says the Greco-Roman and Norse and Amerindian and every other mythology's gods aren't real and stomping around? Not to mention there's demons kicking around. One reason martial artists have such complete autonomy might be that for most of existence, they're the only defence anyone had against rampaging gods, demons, and other martial artists.)
Although, from my recollection, the airport was deserted of civilians and swarming with police officers (knocked unconscious and later mind-controlled), which would sort of explain what the city was doing. Doesn't give any explanation for what Ranma, Ryouga, Akane, Kunou, Kodachi, Ukyou, Shampoo, Cologne, Mousse, Happousai, Mikado, Azusa, Mariko, Sentarou, Satsuki, Hayato, Konatsu, Hinako, Soun, Genma, et al are doing, though.
And as far as your zoning concerns go, Necrotoid, I must ask the question: "Who, precisely, enforces this zoning?" Ranma martial artists are effectively above the law; they do whatever they want and the law conforms to them. This is seen in many ways in the series, and it's also notable that when a martial artist or monster makes trouble, the legitimate authorities (like the police) go to martial artists to solve the problem (like Soun Tendo). So too, can Ranma wear whatever uniform he wants at school, fight with the teachers, have a non-standard haircut and take off whenever he feels like it; Kunou gets the same priviliges, and martial artists can cheat outrageously at sporting events without repurcussions. Who's going to tell Ryuu Kumon he can't build his new dojo whereever the hell he wants? The Chinese Communist government stays silent when two giant monsters, one throwing lightning and fireballs, fight each other over Shanghai; neither they nor the Japanese SDF have a military response to mountains getting destroyed in the course of battles by the gods that walk among men... you think some random Japanese cop is going to push a guy around who could punch down a building? And these people aren't that rare - there's apparently one or two in every high school, and nobody's that shocked over the feats they can do. That says nothing, of course, about the fact that in Ranma 1/2 Shinto is undeniably real, because the gods can show up and fuck around with you if you piss them off. Magic is real, and there's people out there with power that more than rivals nuclear weapons. You want to fight a martial artist? Don't get a gun, you silly norm - they'll hit you six times before you pull the trigger. Buy one of our battlesuits that feeds off their chi and makes you an ubermensch too! But be careful, that technology is unstable!
If the world's technology and governance is similar to our own (and every indication is that it is, with a few exceptions), then law and order and government by non-superpowered people exists only at the sufference of the demigods who stride the earth fighting their private little battles and pursuing their personal goals. And that's JUST Ranma 1/2. When you add more things to the mix, regular folks get inevitably more and more impotent. It's the inevitable consequence of a pyramid - the higher the spire reaches, the more bricks must be at the bottom and the deeper they're pushed into the mud.
(Edit: Oh, and it's worse than that. Shinto isn't the only religion with real gods - there is a god Asura, and that god has real power. The Asuras, demon/Hades-analogues from Hindusim, came from pre-Hindu myths... if that means all the Hindu deities exist... holy crap. If all the Taoist ones do too... holy CRAP. And then who says the Greco-Roman and Norse and Amerindian and every other mythology's gods aren't real and stomping around? Not to mention there's demons kicking around. One reason martial artists have such complete autonomy might be that for most of existence, they're the only defence anyone had against rampaging gods, demons, and other martial artists.)