Cars are subsidized via road building/maintenance, after all, and it's likely to cost less to maintain a few bikes than it does to maintain roads/parking for the cars that would displace them.
Imagine if there were no transportation subsidies and road maintenance were privatized. A nightmare. It seems entirely reasonable that forms of transportation that can help bring tax revenues to a city are subsidized, and therefore entirely reasonable to create a start-up based in part on those subsidies.