Yes, there is a mix of taxis and probably the cars outnumber trucks (depends what you're doing, if it's long distance you wouldn't want to take a taxi because of cost, and I guess they have tuk tuks too). Neither are great because of the traffic and pollution caused by all the other road users. So Bangkok is a terrible example of a place which needs more taxis, as if you want to go any distance at rush hour they are terrible, and they cause all sorts of problems (pollution, noise, traffic) - it's one of the worst cities I've been to for traffic.
The public transport there is good (what there is of it), but the BTS and MRT are both expensive and therefore underused by anyone other than tourists and business people - most people don't use it and it's not as extensive as other cities. At least when I've been there the skytrain is remarkably quiet compared to the streets given how quick and easy it is. It's a shame they won't tax the cars more in town and use the money for improving public transport instead IMHO, and Bangkok is a terrible example of a place which needs less regulation - they need far more regulation on their taxis and traffic in general in order to manage it as at the moment it is bedlam at rush hour, partly because of all the taxis, motorbike taxis and trucks. It is a great example of the free-for-all which results from unregulated capitalism though.
Skytrain is packed during rush hour, but it's not as packed otherwise. It seems to go everywhere I need it to when I visit Bangkok, though.
Beijing cut the subway to 2 yuan during/after the olympics (it was 4 yuan before and even in 1999 it was 3 yuan). The result is that the subway is very elgalatarian and very packed; I avoid it for the taxi accordingly (spend about 80 yuan a day on taxis). But Beijing traffic is also worse than Bangkok's, and there is more regulation (no private minibuses, not many tuktuk that are useful). Whatever they do, the answer to our problems probably isn't more taxis but public transit is also a problem (for the middle class).
I like Japan the best, where the transit is affordable, convenient, and mostly comfortable (when not rush hour).
Where China is harmed by their overregulation they are helped by their practice of creating laws and then selectively enforcing them.
In Zhuhai (near Guangzhou) there are far less taxis on the street than demand would dictate, however plenty of citizens drive around offering people rides at similar rates and everybody uses them, locals and foreigners alike. It is obviously illegal but it is so widespread and common (happens right in front of you and the police on every major street all day) that it is clear the police aren't doing anything about it.
That system is very Chinese. They make laws that would seem to restrict business and then local officials tell the police to ignore them when they deem their area is better off without them. Unfortunately this also extends to things like drugs and even kidnapping in some areas. No system is ever perfect.
The public transport there is good (what there is of it), but the BTS and MRT are both expensive and therefore underused by anyone other than tourists and business people - most people don't use it and it's not as extensive as other cities. At least when I've been there the skytrain is remarkably quiet compared to the streets given how quick and easy it is. It's a shame they won't tax the cars more in town and use the money for improving public transport instead IMHO, and Bangkok is a terrible example of a place which needs less regulation - they need far more regulation on their taxis and traffic in general in order to manage it as at the moment it is bedlam at rush hour, partly because of all the taxis, motorbike taxis and trucks. It is a great example of the free-for-all which results from unregulated capitalism though.