According to a Reuters report, at the site of at least one stop, there appear to be private security guards monitoring the drop-off and pickup of employees.
On two successive days this week, two men waited at a stop in San Francisco's Mission district for Google's shuttle to pick up employees, though the men did not admit to being security guards, according to Reuters. Before the bus left, a driver waved them off. The article describes them as follows:
Dressed casually in jeans and wearing black ski hats or hoods, the two men did not stand out from the dozens of other young tech workers waiting for the Google bus. On close inspection, each sported the curly wire of an earpiece, and one occasionally jotted notes down on a yellow stick-it pad.
The article also indicated that it's unlikely the men would be armed, instead working more as a liaison to the police.
Google did not reply to a request for comment, but we'll update this post if we hear back.
Another source of resentment has been the shuttles stopping in areas designated for Muni, the city's official public transit system, without paying a fee. Earlier this month, San Francisco announced a pilot program in which the shuttle companies would indeed have to pay to pick up passengers at those stops.