I had the anti-self-checkout mentality for a bit, because I didn't want to see cashiers losing their jobs. One day at Target I was waiting in line at the human checkout, and the cashier started yelling at everyone in line that there were multiple self-checkout machines open. It sounded like she hated our guts.

Fine! I'll use the damn machines. Haven't bothered cashiers since then if I have other options.

edit: to be clear, I'm not blaming all cashiers for her attitude, I just want to do the right thing without being a pain in anyone's ass and I've learned that sometimes that means using self-checkout