The new venture-backed private transportation service Leap began offering rides in San Francisco last week in a swanky shuttle meant to feel "more like a living room than a bus." A ride with the service, which costs $6 one-way or $5 in bulk, comes with WiFi, USB ports, a laptop bar and locally made pressed juices (for sale on board, that is).

Most of the passengers on-board at first appeared to be skeptical journalists. Private mass transit is a touchy topic in San Francisco, where many fear the tech industry is creating parallel amenities — private campuses, private transportation, private cafeterias — where tech workers don't have to bump into the masses. With this latest twist, Leap and a few other startups, are offering up-scale rides to anyone in the public with a smartphone, although the intended clientele here still seems to lean toward tech. Leap so far is running one route that collects and drops off commuters around a hub of tech offices downtown.

The San Francisco-based private transportation company Leap produced this ad, which showcases its "swanky shuttle" service. (Michael Victor/Leap)

Services like this, though, raise some broader issues that are not particularly unique to San Francisco, nor to the tension the tech industry has created there. Public transit is ripe for disruption — that's why investors are backing these ideas. If you were to look around any city and try to identify a problem in need of lucrative new solutions that emerging technology might provide, the dreaded commute is an obvious one. Public transit can be inefficient, unpredictable, slow, crowded, or on its worse days downright broken. Transit needs a shakeup.

But as private providers increasingly offer what looks like a first-class alternative, the risk isn't that companies like Leap will eventually replace public transit; it's that they'll turn it into even more of a ride of last resort used primarily by the poor. If Leap is successful — and it's entirely likely it won't be, because a transit system is incredibly costly to operate — San Francisco and other cities could wind up with one public bus system for all the people who need a $2 ride, and one private bus system for the people who want to sip a $7 iced coffee on the way.

This would siphon needed fares from transit systems. But it could also sap public willingness to invest in them. The answer isn't that higher-income riders should have to use poor public transit because lower-income riders do, too. It's that we should throw innovation at the problem of public transit itself, not simply at the promise that some people could afford a work-around.

In other parts of the world, we already know what this might look like.