AIBU to think it is rude to start putting stuff on the conveyor belt......

[JobStresserxo]

at the supermarket before the customer in front has finished loading their shopping?
Happened several times to me just recently. This morning, I had to ask the customer behind me to allow me more room on the conveyor belt as she hadn't left enough space for me to get my shopping on.

I have been known to say excuse me when someone trolley blocks the whole belt, especially if they only have a few things left to load, with plenty of space for my items, and there is a queue building. It's kind of passive aggressive to trolley block if you don't actually need all the space.

Stay at the back and load it there, pushing it forward as you go.

I prefer not to 'push' bread, eggs, soft stuff too much, if at all possible.

Back of what? I presume nobody waits until the whole belt is empty before they start unpacking.

Though considering that at the other end there are people who only start looking for their wallets when they've packed all their bags. I suppose it's possible.