Are you sure that's not "the bus driver is waiting for his clock to read the scheduled departure time" or "the bus driver is waiting for people to pay their fare and board the bus" or "the bus driver turned the bus on early to warm it up"?
Every bus I've ridden in has signs plastered all over the front saying how you need to idle it when starting up / shutting down the bus to avoid destroying the innards, so I would expect there to be long horizontal lines at the start/end of runs but I wouldn't expect that to be indicative of drivers being "lazy".
Am I sure? No. That's why I said I didn't know if they were waiting for dispatch, or something else. But I find it implausible that those sorts of delays would cause nearly every departure to be 10+ minutes late at the start of the route, as they seem to in these plots.
Also, I have a lot of direct experience with drivers on certain lines just sleeping in the back of their buses until past the departure time.
Hang out around Embarcadero Station during evening rush or 4th & King sometime. It's a real mess. I've seen 4 busses running back to back, and some mornings I'll see 5 or more trains backed up. Not to mention the entire system already runs at a snail's pace. I generally bike, and I will usually get there in about 1/2 the time. Compare to Chicago where there's no way I could outrun a CTA bus, let alone the trains.
Yeah, that's fine. I expect delays at rush hour. I don't expect to see nearly every departure for nearly every line delayed by ten minutes or more. That's what these plots seem to be suggesting.
Every bus I've ridden in has signs plastered all over the front saying how you need to idle it when starting up / shutting down the bus to avoid destroying the innards, so I would expect there to be long horizontal lines at the start/end of runs but I wouldn't expect that to be indicative of drivers being "lazy".