Why do cabin crew make going to the loo on a single aisle jet with rear loos a logistical nightmare

since the drinks trolley always seems to be blocking the aisle. Firstly you have to walk at crawling space as they inch along the aisle. Then eventually when you've been standing there for about 10 minutes they actually NOTICE you, ask you what you are doing? (what do they think I am doing?) & if there is a spare seat they ask you to sit there. You either have to wait till they serve the whole plane & hop from one spare seat to another or if you're lucky they will EVENTUALLY reverse back past your seat & let you on your merry way. Inevitably they same happens on the way back & an operation which should have taken five minutes ends up taking 15-20 minutes & when you eventually collapse into your own seat, your fellow travellers gawk at you as if they thought you been sucked out of the aeroplane.

This is a SERIOUS question.
SIERRA