On another outing we had decided not to go on a museum tour and I suggested we could go for coffee and meet up with the rest of the party after their tour.
The other ladies were reluctant as Betty the leader might not approve!
This is irrelevant and nothing to do with rules
"Betty" gave her time and knowledge to book an outing for a group to a museum, presumably on a coach.
Thers were no rules, but perhaps expectations that, having booked the outing to go to the museum, that is what people wanted to do.
And perhaps someone else might have wanted to go on the trip but there wasn't a place available.
As for Entrance and Exit - as ilovecheese said, that would be for safety reasons.
Petty rules can be questioned, of course.