If cars had no externalities just building more and more roads would probably be a good strategy. But cars have high externalised costs. There is of course the

If cars had no externalities just building more and more roads would probably be a good strategy. But cars have high externalised costs. There is of course the environmental aspect and accidents, but, perhaps less obvious, due to poor space utilization, more car infrastructure makes cars all but required since density becomes so low that walking or cycling are right out and public transport has no chance of being remotely cost-efficient (or convenient, who wants to walk ten minutes through a parking lot to reach the store after getting there by bus?)