Why does the self checkout and bagging area have to be so low and uncomfortable to use?

It's based off of an average height, for most people It's fine.

Because people are usually distracted and inconsiderate. I don't have any issues whenever I shop in. Delivery would be your best option I'd say. Try it out would be great and convenient for everyone.

Why do doors open ?

That's the fastest & easiest way to check out! Sounds like user error. Goin to an actual cashier is slow & uncomfortable

Good question