Canada

FYI to anyone here, you don't have to show them your receipt or let them check your bag. Just refuse and leave.

Any before anyone says "they'll ban you from the store", they very likely won't. And even if you are added to the ban list, it's not really possible for them to enforce. I worked at a very high traffic Loblaws for a while as a self checkout attendant, and I would regularly have my friends in customer service point out people that had been banned checking out with no problems.

Any time I’m buying more than 3 items, I typically just go straight to a human-operated register.

The grocery store near me has the most annoying security feature on their self-checkout machines. After you scan your item, it must be placed on the checkout shelf before you can do anything else. If the weight is “unexpected”, you’re stuck asking for help. If you have a full cart of items, you can’t parallelize tasks because of this deadlock; the machine refuses to scan the next item until your current purchase is on the checkout shelf and verified.

As non American with no self checkout available, what does the recipe check look like? Do you just show them recipe and they briefly look at it before waving you through or do they actually go through all of your groceries cross checking the items?

Because we still have to sometimes show the recipe to the security guards despite not having self checkout. But they don't cross check anything and the procedure takes 2-5 seconds as they sometimes sign the recipe.

You don't legally have to stop and show your receipt (except Costco). I have a friend that pont blank tells them "nah" every time. Catch is, security can legally detain you if they really suspect something.
For me it's not worth the hassle and I just show them with an annoying look.

Having said that, I’ve noticed myself making mistakes. I’ve accidentally failed to scan an item, and I’ve accidentally entered incorrect codes for produce. When I notice, I fix them, but I’ve probably missed a few.

Stores are 1000 percent alright with this. They don't want you to intentionally steal of course, but shit happens and people mess up, even trained cashiers.

The real problem occurs when people intentionally and maliciously steal, and these checks arent there to catch people like you.