The touch screens allow us (I work in backend retail) to push updates to hundreds of shops across a region without having to update those mechanical keyboards. It's a huge benefit to the industry. Before, when a new feature was added we had to send a human technician out to every one of those shops. Or get the shop managers to replace the key, or sticker the key. You can see how much easier it is to push updates over a network compared to the alternatives.
As for scanners, they vary a lot in design and intended purpose but with some optimization and testing they are are always better than the emerging tech for scanning items; your smartphone camera. The industry is heading toward you doing the scanning yourself (albeit in addition to the traditional shop model). Phone cameras are a pita having not been designed for this purpose. I don't see any IR scanners being available to the general smartphone market any time soon, but they do exist as 'jackets', mostly for tablets.
Makes sense. The mechanical keyboards had dedicated keys for the most common produce items, but maybe 10-20% of them were not applicable at a time due to being out of season and/or not available for some reason.
I worked in Tesco in the 00s while I was studying, and when I first started the checkouts had physical keys with some quick access keys on the side of the screen which changed depending on the context. The normal keys had a rather satisfying mechanical mechanism, where as the quick access keys just used a conductive-rubber mechanism so were a bit harder to press.
When I first started there was a menu driven by the mechanical keys so if you didn't remember produce codes, you could use this to go through everything. The systems were networked and these menus were updated regularly with seasonal products. To get to potatoes (for example) you would press Menu, Down, Down, Enter, Down, Enter and be presented with the different types of potatoes. You could even hit the keys in quick succession without waiting for the UI to update, so it was pretty quick if you knew what you were doing.
Later they changed the system to instead of being driven by the mechanical keys, to use the quick access keys. These were harder to press and you couldn't press them in quick succession - you had to wait for the UI to update before pressing them.
Just before I left they started phasing out the physical buttons, and I think all the new checkouts are touch-screen driven which I assume is even worse. Under the hook they (were anyway) running Windows XP, and the same software.
As for scanners, they vary a lot in design and intended purpose but with some optimization and testing they are are always better than the emerging tech for scanning items; your smartphone camera. The industry is heading toward you doing the scanning yourself (albeit in addition to the traditional shop model). Phone cameras are a pita having not been designed for this purpose. I don't see any IR scanners being available to the general smartphone market any time soon, but they do exist as 'jackets', mostly for tablets.