None of those had a photo of the tunnel entrance… why is there a rail tunnel that’s easily accessible to cars? Here in DC, the Metro is completely segregated from auto traffic. Is the SF rail running on streets?

Here's one of the entrances on streetview: https://www.google.com/maps/@37.7694654,-122.4291885,3a,75y,...

The SF MUNI system has light rail vehicles which do sometimes run on surface streets, similar to a trolley.

Oh, well I can totally see how a car would end up there if it was dark, stormy, or the driver was drunk/high. We gets cars on the local bike path all the time - usually a drunkard, but sometimes just somebody who thought it was a driveway.