Often it seems to depend on the machine settings too. E.g. in the UK Morrisons and the Co-Op seem to use the same hardware in many branches, but the former is v

Often it seems to depend on the machine settings too. E.g. in the UK Morrisons and the Co-Op seem to use the same hardware in many branches, but the former is very reliable and most "unexpected item events" I see are user error, whereas the latter seem to have a good 30% chance of complaining about the weight of your item even when you've done everything right The other big difference in smoothness of experience is having sufficient staff to come and deal with problems. Firstly, because user or machine error will always be non-negligible, but also because age challenges are quite common too. It's frustrating queueing and seeing a good 4 or 5 machines in a blocked state (and sometimes abandoned due to it) and there being no or insufficient staff around to unblock them