wait is this an age thing? everyone i know under 25 uses the machines and everyone over 50 does the person line. my mom will wait 10 minutes to not use the machine and i genuinely dont get it

It is partly an age thing. I use the machine because my grandson showed me, and I still miss the greeting. In Japan the cashier says the amount aloud and bows. The machine says "unexpected item". I prefer to be expected.