I think that this amounts to a small pebble in the mountain of technologies that have to be developed to enable AVs. Here's an easy solution: every bus stop ha

I think that this amounts to a small pebble in the mountain of technologies that have to be developed to enable AVs. Here's an easy solution: every bus stop has a kiosk that dispenses a RFID bus pass if you put in your payment info. Then, when the bus comes, you can enter from any door and the RFID receivers detect your presence. Attempts to board without a bus pass are detected with weight sensors and a camera network (current computer vision techniques are probably reliable enough for this application; they'll be even better in a few years). Unauthorized persons are advised to get off at the next stop by audio recording and identified by displaying a snapshot of their face (taken earlier on the bus). If they don't get off the transit police are summoned.