It all seems very unnecessary. I don’t really understand why someone wouldn’t show proof of payment if they had it. Unless the inspector had made a bee line for her on the bus and made her feel uncomfortable. A friend of mine was burgled recently and they didn’t even pop round but four officers for a couple of quid fare.
Buses have shitloads of cameras, take a photo, identify persistent fare evaders, take action but really the police seemed unnecessarily physical over a bus fare.