This one gets me every time. I’ve only ever seen a couple super markets or stores implement this for human-operated check out stations. Ross has this, and Best Buy used to during the holidays.
At least at Safeway I can spot the kind of person who looks like they value their time and it'll usually go faster.
I'll literally never shop at Ross again because it takes forever to exit their damned queue.
The model works better at Trader Joe's in SF where it's mostly people who value their time. You can then be confident all the counters won't be used by slow people.
I would honestly be fine with making that permanent. It's so much easier to pick the things I want with fewer people between me and the shelves. All in all a much more efficient shopping experience.