What a bullshit. A certain person at Costco had the decency to own up to the mistake. Another Costco employee could have reacted differently and try to pull your leg. Same with ANY other company. There are good people, and not so good people.
„One tech always rolls his eyes or has some off handed remark when I come in too“
Have you ever considered why that is? Maybe he had a bad experience with YOU. Maybe you have been unreasonable, insulting or a know-it-all (some customers can be super annoying). There is always a reason why people react to other people as they do.
And there are people who can stand above their feelings for someone, despite finding them total asswipes (which they probably are) and stay professional. Not everybody can, even though I wished everybody could.
Everything is people business. It‘s not right to say that a whole company is good or bad based on, seen from the greater scheme of things, a single or several negative experiences with a small group of representatives. It totally depends on who you talk to / interact with.