If you look at the bikes typically used for bike sharing systems, you'll see that these things resemble the kinds of bikes you and I would consider viable bikes only superficially. These are purpose-made to a very different set of criteria and usually include things like built-in locks, radio tracking device and associated battery/charger, a dropped down-tube (i.e. a girly-style) frame, wide sprung seat, and large flat-proof tires. They often also have racks and all sorts of reflectors. Remember that they market these things at city planners not individual bike buyers. Planners are looking for longevity, low-upkeep, long-term reliability, etc. I think they also seem to prefer bizarre looking design vs. traditional bike styles.