In the past couple years, the bus has become an unlikely and divisive symbol of the way the technology industry has changed the face of San Francisco. Fleets of sleek charter coaches ply the streets of the city's upscale or up-and-coming neighborhoods, ferrying tech workers to and from their jobs at faraway Google, Apple, and Facebook. When activists want to protest gentrification, inequality, or other social ills, tech shuttle buses make for an irresistible prop

Could private buses ever be a friend to people who want to live and work in San Francisco? That's the thinking behind two billionaire-backed startups with confusingly similar names, one of which launched service this week.

Leap, whose investors include Andreessen Horowitz and Salesforce CEO Marc Benioff, began operating a limited service between the Marina residential neighborhood and the Financial District on Wednesday. It joins Loup, which maintains two similar routes and is backed by Twitter co-founder Evan Williams's Obvious Ventures.

(There's also a startup called Chariot, but it offers a somewhat different proposition: Its vehicles are vans, not buses, and users can establish new routes by crowdfunding them.)

Leap and Loup can be seen as bridging the already narrowing gap between private car or taxi service and public transportation. While the ride-hailing apps Uber and Lyft have revolutionized the experience of getting around San Francisco, where municipal transit and taxis can both be hard to come by outside a few corridors, they're expensive options to rely on for everyday commuting. Demand-based surge pricing also makes it risky to count on them during rush hour, when rates can double or triple.

Both Uber and Lyft have sought to lure commuters with lower-price carpooling services introduced last year. Lyft CEO Logan Green revealed this week that Lyft Line now accounts for more than 50 percent of the trips it provides in San Francisco. Uber has been discounting its UberPool feature to attract new riders, guaranteeing rides anywhere within the city for $7.

Leap is even cheaper than that, with a ride costing $6. While protesters may fume about the big tech companies' "luxury buses," they are, in fact, relatively light on creature comforts. Leap vehicles, on the other hand, feature leather and wood interiors, Wi-Fi and USB ports, different styles of seating for working or socializing, and snack vending, with Blue Bottle coffee. Most enticing of all, perhaps, an app allows you to track your bus and watch it approach to minimize wait time. 

And, unlike the hated tech shuttles, Leap's buses don't compete with public Muni buses for pick-up points--a smart move by a company that wants to be seen as easing the stress of San Francisco's tech gentrification, not aggravating it.

With Uber now valued at $40 billion, the financial payoff of improving on the transportation grid is hard to ignore. But when I asked Williams about Loup during an interview in December, he talked about its mission more in social-benefit terms.

"Conceptually, I think it's cool because it's about creating a private, Uber-like model that, if it's successful, will be comparable to prices of public transportation," he said. "I think transportation's interesting, I think getting more cars off the road is interesting. It has a very direct benefit if more people use it."