In any case, considering how dense is the traffic in the airspace above the Bay Area, I'd imagine that they've had to come up with something more sophisticated than people with binocs.

Yes and no...They do use people to spot for planes, they also have a radar to detect planes. The spotters do not use binoculars (That would be counter productive). The spotters have the ability to shutter the beam if they see a plane approaching. On Mauna Kea the beam is shuttered if a plane gets within ~25 degrees of the beam.

I was there on one of their laser nights, planet hunter Geoff Marcy was visiting there that night. There was also a group testing out a AO system for amateur telescopes. It was an interesting night.

I was there to prepare for my interview at Keck.
One of the Lick AO engineers took me on a tour of the scope and laser... (It was the first time I had actually seen a big observatory- I was blown away). It was nice how willing the staff there was to let me have access... One thing I have learned is that scientists love to share what they work on.

Seeing the system in operation was a big help...

You will not see the laser from that distance, the beams on Mauna Kea are not visible from more than a km or two.

Do you have any plans to come to Hawaii? I would be happy to give you a tour...