Lots of people get on a buses and show the driver a pass. Bus passes were invented shortly after conductors hit the road. Back in the good old days, you got on a bus and went and sat down and waited for the conductor to turn up and ask you for your fare. Then some bright spark decided that it would be more economical if the driver asked for your fare when you got on. Saves money paying the conductor. The big problem with this idea is that it now takes 60% longer to travel the same distance so it costs only slightly less per journey than it used to as it takes longer so you have to pay the driver more because the same journey takes longer but the driver is still being paid an hourly rate. The second problem is the bus spend more time at each bus stop blocking the road while he is collecting the fares. So passes were invented. You buy a weekly pass and show the driver when you get on. Saves time finding the money, paying the fare collecting your ticket and change. It didn't take long for some passengers to notice that when the driver is driving and collection fares he wasn't really noticing that they weren't getting of when they should. Or even that the pass was valid. So if you travel you could, if you were that way inclined get away with murder; or at least with not paying the correct fare. Or even any fare. Passe should make things got quicker but now I am spending so much time checking them because so many of them are invalid.
To day someone got on with a pass that was over a month out of date. He was most upset when I noticed and took the pass off him and made him pay. But this was just one pass. When you are busy driving and trying to collect fares and notice who is over riding plus all the other things that go on in and around the bus you just don't have the time you need to check every thing that needs watching. That is what Inspectors are for. To get on buses and look at tickets and passes to check they are valid. Shame it doesn't seem to happen very often.