My step-dad would raise his hand and say “Teacher!” when they were in ear-shot.

Never got why my mom hated it. She’s more of an “Excuse Me!! Let me tell you my life story while you refill my water! No ice please!”-lady.

No, this is a reasonable reaction.
Any balanced person would feel this way.

In Brasil, if you don’t call your waiter/waitress they are not coming to your table.

Meanwhile my autistic ass just sits for a long time until they look my way and I wave awkwardly hoping I didn’t do anything wrong

You snap your fingers, I snap your neck