From Planetizen:
App-driven bikeshare, without the station, has been spreading rapidly, especially in China. But the system comes with its share of problems, including its own version of the tragedy of the commons.

With two Chinese companies leading the charge, dockless bikeshare is popping up in cities the world over. New York City, San Francisco, and Washington D.C. are all experimenting with the technology. But there are potential pitfalls. Dominic Rushe writes, “Unlike docking rental services, which require bikes to be returned to a fixed docking station, you can leave your ride wherever your journey ends, practically. And therein lies the problem.”
Large-scale dockless bikeshare is vulnerable to vandals and thieves, and legitimate riders have little reason to treat the ubiquitous bikes well. “In China, where there are some 16 million shared bikes on the street and MoBike alone now has over a million, the authorities have been forced to clear up ziggurats of discarded bikes.”

It’s another iteration of the tragedy of the commons. “With bikes literally littering the street, riders become less mindful of how they treat the bikes and where they leave them when there is always another to pick up.”
U.S. operators are keen to “maintain decorum.” Meanwhile, “DC’s dockless bike experiment is a beta test designed to run through April next year. It seems to be working beautifully. The city already has close to 4,000 docked bikes serving two million-plus riders a year with its Capital Bikeshare system.”