I sympathize. This afternoon I went to the store to pick up a few things and since it was just a few I used the self checkout. Well there are six, set up in two rows of 3 on either side of the cashier stand.
So like this where 0 is the cashier stand and the X's are display stands of goods.
front of store
I 0 I
I X I
I x I
where line forms
The first one on the left I pulled up to had a sign saying "Please wait for cashier" as soon as you hit the "start" button and there's no way for the user to undo it.
And there was someone in front of me at the next one down, but as soon as they left, the woman behind me huffed and went around me, and before she started, the person at the very last one on the left finished and headed out. Did huffy lady move forward?
Nope, she stood right there, but not only did she do that, she parked vertically, thus blocking anyone with a cart from getting through to the first register. Eventually the person at the register across from her left and I was able to move over but sheesh.