The G81-8XXX series keyboards have that card reader on them.
Or other types of card readers, or interfaced to devices. I had got one without a card reader but a big DIN socket on the side, a DE-9 on the back and some electronics inside that I don't know what it is for.
Not used only as POS. Some workplaces such as banks and police stations use key-cards as a second layer of authentication of users.
Only the front is like a RS-6000, the rest of the case is quite different and might not be compatible with G81-3000 or G80-3000 on the inside.
The stabilised keys are different - modern MY switches have the stabilisers integrated into the switch and caps.
A G81-series keyboard with doubleshot or winkeyless keycaps have stabilised keys that are compatible with Cherry MX, but the Space Bar can be either-or and 1.25u bottom row keycaps are always off-centre.