There is a lot going on here. I will bet most will disagree with me.

On Narrow Body aircraft, when we are doing service, the only bathroom behind us is the one in First Class. We can't move the cart out of the way (well we can, but it would cause service to take hours) so we let passengers behind us use the one in First Class because they can't actually go to the back.

Some FA's are super strict and a little nasty/mean about forcing people to use the back bathroom. I am not one of them, ever since I had a racist woman get in my face for allowing someone of a different skin color in the back, use 'her' toilet in the front. So now, I let anyone who wants to use it, use it, with discretion. I kick people out of the front when there is a line because it's a security issue. But sometimes if there is a middle restroom like on some 737's I will wave for ONE person to come up if there is a long line. It's really, for me, about discretion.

What is more messed up is seeing two rich businessmen in First Class fighting each other over bin space on an airbus. (not enough FC bin space) but that's another issue.

Point is, for me, I take a middle of the road approach. If it's one person fine. If it's 50, then no, go to the back. I think it's about trying to all get along and through the flight.