Is it peculiar to the south, or simply any part of China (minus Beijing) that has any kind of development? There's a very common Chinese expression - "Heaven is high, and the Emperor is far". If the demands of distant rulers aren't energetically enforced, most people don't pay attention. Heck, if you get away from Chang An street (the bit where Tiananmen square, Mao's memorial, and the Chinese national parliament are located), most of Beijing's backstreets are pretty relaxed. Unless you commit a violent crime, piss off an official, or are actively revolting or dissenting the Chinese legal system does not care.
The downside is, China seems overly reliant on two sources of revenue - land sales, and the profits of State Owned Enterprises (government-owned companies). Income and corporate taxes are something of a joke, unless the company paying them is either large, foreign, or both. Given that SOEs suck up all the capital (moral hazard - the government won't let them go bust so banks love loaning them money) and really inefficient (especially if you account for their free or cheap land, and special considerations, though on the other hand they can't break the law as much as private companies), and the damage China's housing bubble might do, they might need to think about a land tax soon (which they seem to be already doing).
My guess is that the 'Wenzhou' model is everywhere to some degree, but I only really know about where I live (Fujian).
I think there's two factors - (1) is that there haven't been many great places to invest money, so rich people throw them into houses, stock bubbles and 'alternative' non-legal investments (like lending groups). (2) is a generalisation, but Chinese people tend to be quite speculative - I guess a few years ago the average Brit would be happy with a 4.5% return on a 2year bank bond, whereas many Chinese people are more willing to take much riskier investments with possibly much higher returns.
As for ignoring laws, the whole-country model (not just Wenzhou) is that many laws are ignored until the government decides to crack down on something. When they decide to crack down, you react quickly. So, for example this month in Fuzhou it's fire safety month, and everyone is suddenly getting their fire-safety certificates in order. Next month it might be traffic, or health... who knows :)
The downside is, China seems overly reliant on two sources of revenue - land sales, and the profits of State Owned Enterprises (government-owned companies). Income and corporate taxes are something of a joke, unless the company paying them is either large, foreign, or both. Given that SOEs suck up all the capital (moral hazard - the government won't let them go bust so banks love loaning them money) and really inefficient (especially if you account for their free or cheap land, and special considerations, though on the other hand they can't break the law as much as private companies), and the damage China's housing bubble might do, they might need to think about a land tax soon (which they seem to be already doing).