I guess we must accept that things work differently in different parts of the world. It works fine here and no one gets either pissed off or is in the way.
How much space is there inside the store for people to do that past the registers? Because here, there’s room for about two carts and no table to do it on. Then in the parking lot, if the weather isn’t terrible (it can get down to arctic temperatures and blizzarding here in the winter), you have to hope you leave enough room, if there is enough room to leave, for other cars to get by you.
The only place I have ever been to in the U.S. where bagging your own groceries was feasible was Aldi.
It’s simply a different system. The markets are adjusted to it. There is enough room and sometimes even tables for this purpose. The markets are simply using different mechanisms to speed up the process so that they can have more customers per minute. Aldi is a big player here. The cashiers are trained and drilled to be super fast. There are no baggers, but enough room to pack your stuff yourself later. Recently they added a new kind of “double line”. Now there is enough space for two trolleys right behind the cashier. Each line has their own card reader. The cashier has minimum waiting time for the next customer. Also almost zero time for customer interaction or any talk. Probably effective, but it really feels rushed out.
The only way you could add space would be to take out and move all the checkout lanes.