I agree. As the saying goes, "you rarely see a bookie on a bicycle"
When I was a teenager, I used to work evenings and Saturdays in a local amusement arcade for a bit of extra cash. The old style fruit machines were set to a payout level of circa 70%. There was also a way of telling whether a machine was 'due to payout'. As people played the machines, the payout tubes were replenished with the money they were putting in. When the tubes were full, the money would fall straight through to the cash box in a locked box at the bottom of the machine (which we would empty each evening). Working there, I could recognise the 'clunk' as the money hit the bottom cash box. I could lurk until someone gave up or run out of pocket money and then step in. Was not by any means foolproof but certainly paid for a few of my Saturday nights out.