You can get randomly selected upon checkout where they will sample a few items from your bag, and if it finds a discrepancy they will rescan every item you have.

These hand held scanners have been a thing for over 10 years, way before the current iteration of self checkout stations. They continue to exist side by side with self checkout stations at supermarkets mainly.

It also should be noted that I have not seen a single self checkout station in the Netherlands that puts restrictions on how you scan your items. It doesn't care about weight and in what order you scan and put items into your bag or if you just keep holding the items, and I never have any issues with this system breaking or complaining about anything.

Scan as you shop minimises shoplifting by requiring random spot checks. When you about to checkout, person comes and re-scans few items in your bags, if all were scanned you are good to go.

We have that in some places in the US as well. Stop and Shop has little mobile scanners or apparently you can use an App instead. They say they might randomly check your bags when you leave, but it only happened to me once.

HEB has those now. They also do a weight check but they just weigh your entire cart at the end.