We used to have that in some of our supermarkets years ago, but they've all disappeared over the years. It's all a mix of self-help checkouts/human checkouts now. Not sure why.
One of my local grocery stores has these mobile scanners and I strongly prefer it. I’ll go slightly out of my way to hit this store instead. While I am loathe to give Amazon more data/consumer insight and see this as massive consolidation play, I suspect people will, once accustomed to it, totally normalize this and not look back.