Think of it this way: imagine the gov decides that cars are too expensive, the barriers to entry are too high. They want everyone to be able to have a new car. Employment will increase, people can take jobs where the busses dont run. So, they relax the rules that currently demand a certain level of crashworthiness, and things like airbags or ABS or traction control, etc. Removal of these impediments now enables GM to make a brand new (unsafe) car for $4000, which everyone can afford.
Of course, the gov is not compelling GM to make such cars, nor are they compelling poor people to buy them. All parties could choose to do nothing differently. Anyone who is not incredibly naive would realize that of course GM will start to take advantage of this, as it means more $ for them. Now the poor ditch their bus passes, without stopping to think about what it means to your face if your car does not have tempered safety glass and it hits something. After all, the president wouldnt let me put my family at risk, right ? Hooray, now we are one step closer to a classless society where everyone can own a new car.
Of course, take a look at traffic fatality statistics in a few years time, and tell me the gov had nothing to do with it.