I don't mind them. Where I do grocery shopping there aren't any, but even if there were, I'd still prefer going to a cashier in fear of messing up something. Even if I'm somewhat introverted, saying "Hi" and "Thanks, have a nice day" isn't particularly hindering. As for whether they're job killers I'm not sure; at that same place employees that are doing check out are doing everything else around the store as well.

I prefer self checkout when I'm only buying a few items, which I usually am. The problem is when people try to bring full carts through the self checkout; that takes forever.

As an introvert as well, nah gimme my cashiers back. Annoying ass self check-out machines, make one error and you gotta talk to someone anyway. Then gotta get your receipt checked, because how do we know you scanned everything? So now we're at 2 talkings. Just scan my stuff, cashier, please.

I identify as people.

Oh I hate those. Not because of the job taking, that was inevitable. I hate them because while when I deal with a cashier I can do some small talk, or just smile at someone and remind myself that I am still alive. I can also mask my underperforming brain with words. When I interact with a machine, it screams at me at super high volume to put my god damned item in a bag. Like OK, you don't have to warn the neighbors that I'm a bit slow. They already know!