Years ago I was waiting at a bus stop on Ecclesall Road in Sheffield, As the bus approached, I could see that two passengers were moving along to the driver's perspex cab. That meant the bus would be stopping so I didn't bother sticking out my arm.
When I got on the bus ready to pay my fare, the driver said, "If you want a bus to stop mate, you should stick your arm out!"
"But I could see two passengers were getting off here."
"It doesn't make any difference, You've still got to stick your arm out."
Two weeks later, I was standing at the same bus stop. A number 88 appeared and once again I could see that a couple pf passengers were approaching the bus's exit door. Nevertheless, I stuck my arm out, remembering what the bus driver had said several days before.
When I mounted the bus ready to tender my fare, the driver spoke to me.
"Didn't you see that there were people getting off?"
"What do you mean?"
"Well it's obvious isn't it? When people are getting off a bus it's going to stop so there's no need to stick your arm out!"