Regarding the thing in the middle:

Checkout divider lol

https://x.com/lowgrowls/status/2098500905008341055

Apparently an Europe thing, but some stores have triangular checkout dividers occasionally with larger banners on top.
I've seen them used in my country for "Card Only" checkout lanes.

At most asian grocery stores i go to, its just a long retangular cube. No banner on it or anything. Usuually a long piece of rubber basically.

There's a lot of variants on the thing.
Hollow plastic triangle with advertisement folded on the inside, same but with a square, the banner on a triangular base, chunk o wood, folded piece of paper.

I'm more confused how a belt without those would function, since I have little trust in others keeping their shit far enough away that the cashier can clearly see a difference between customer loads, especially on shorter belts.

Never thought I would see someone explaining dividers.

FWP said in comment #2630015:

There's a lot of variants on the thing.
Hollow plastic triangle with advertisement folded on the inside, same but with a square, the banner on a triangular base, chunk o wood, folded piece of paper.

I'm more confused how a belt without those would function, since I have little trust in others keeping their shit far enough away that the cashier can clearly see a difference between customer loads, especially on shorter belts.

I actually have seen belts without dividers work. Its only for small Mom&Pops shops and the belt is soo small, its like only 2 feet long or something. And even those with longer belts, small community stores that isn't corporate chained just tends actually work cause everyone in the neighborhood isn't assholes.