I’m thankful my grocery stores have a mute button for self checkout. It makes for a much less stressful experience, I don’t know why they have it narrate so much junk.

As for your issues with the inability to remove things, I do know the trick. (I can’t speak for non-us self check out kiosks) As someone who worked as an attendant for the kiosks, the main cause of setting off the thing is picking your bag up before the scale has settled. The scale isn’t just checking that the weight has increased by a certain amount, it’s also waiting to make sure the weight is balanced. The issue with that, is the intuitive thing to do when your bag is full is immediately put it in your cart to make space. So the best thing to do is put your item in, wait a few seconds then you’re set to move the bag. With the small things not registering, could be uncalibrated scales. I have never ran into the multiply issue, as the ones I’ve all been to have scan guns and you can just shoot the barcode a bunch.