>On the other hand, having an "on demand" car service as my only option would increase my transportation costs. I don't think anyone is suggesting it would be

>On the other hand, having an "on demand" car service as my only option would increase my transportation costs. I don't think anyone is suggesting it would be your only option, simply that most people would prefer it because it will be cheaper (since you're amortising the overheads of car ownership over many users). And while owning a car might feel prudent, if taxis become cheap enough, it might not be the best investment for your money anymore.