That's awful! And there's really no excuse for it. In the last year I've really started to realize the importance of kindness, and just trying to treat everyone with a level of respect and decency, regardless the situation. I wasn't a jerk or anything before, and with years in customer service I certainly wasn't a jerk to workers- but something about this last year has made me more proactive in my attempts to just always be pleasant, and if I'm not going to be pleasant, then silent. I think there's a Disney quote along those lines?
What's worse is that most people are perfectly pleasant and normal in their interactions with service workers, but it's easy to forget them and dwell on the person who through a tantrum and yelled at you.
Also, pro tip- in any kind of interaction with a service worker- whether at Disneyland, a hotel, a restaurant- you'd be amazed at how far being friendly with the staff will get you, especially if it's a place you go regularly. Take the time to get to know them, express appreciation for them, write a positive review- and they'll roll out the red carpet for you.