Because they have another Bikeshare choice of what kind of bike to use...? Meaning, people are being given no choice, you'll use the bike as available no matter what the drivetrain. Or we could talk about the preceding Smartbike program: no enclosed chaincase, no dyno-hub...

But hey, if this is what spurs people to adopt cycling amenities like dyno-driven lights, IGHs, and enclosed chain cases, that would be awesome. I tell you, right now though, at the retail level, interest in such bikes as expressed by sales is very, very low.