Some retirees take up gardening. Others volunteer. And some, like San Francisco's Edward Mason, log hundreds of complaints about tech shuttles.

A fascinating San Francisco Examiner article reveals that Mason, a 70-year-old former private military logistics firm worker, is responsible for a staggering 28-percent of complaints about tech buses. SFMTA says Mason has contacted them 282 times with information about private commuter shuttles which are committing infractions.

Like a bird watcher, Mason comes prepared and knows his prey. From the Examiner piece:

The Netflix-bound bus he hunted Wednesday has Texas license plates. This is against the rules of the program laid out by the San Francisco Municipal Transportation Agency, which regulates shuttles in The City, Mason said. Mason recited the license plate out loud, from memory. He had seen the bus on previous hunts, and was out to catch it yet again. He drew his tools of the trade: a pocket-sized notebook, a pen, a miniature snapshot camera and a stopwatch.

Mason has found a litany of shuttle bus infractions, such as blocking Muni access, license plate and permit issues. He's also an active voice at community meetings about the tech shuttles.

It's, of course, a hot-button issue in the city. Many view the private shuttles for mainly tech company workers as a sign of the city's class stratification. The issue has become particularly contentious as more private shuttles hit the roads, using small neighborhood streets and filling Muni spaces.

As for Mason, besides giving him a retirement hobby, Mason says he's become the tech shuttle vigilante because "either it's government not doing their job [or] I just feel it's an inequity and the neighborhood is screwed."