Somedays when you go to work, you just have to check your brain at the door.

Just think of it as obviously being over-qualified for the position.

You don’t want to work for a company who allows that kind of behavior from customers anyways. Hope you can find something better.

Unfortunately many do allow it for fear of bad word of mouth on social media. If it happened in the US most states can fire you for anything

In many of the US states, you can get fired for anything. Or nothing,

I learned that in those types of situations just do what they say and don't comment. As long as they believe they got what they ordered all is good.

You could file a wrongful termination suit. It seems as though the customer didn't have any intelligence for you to insult.

there probably was a latte explaining to do after.

I’m sorry, I meant to order that without the latte.

You should’ve kept your mouth shut and made the plain latte. Stupid people don’t like to have their stupidity exposed, and, unfortunately, they have money to spend. And you know that bs about customer always being...?

Its hard to believe such stupid people exists.

Not defending the behaviour of the customer at all, but just staying quiet like some people here advised is a bad idea, too.
It is important to ask or explaing stuff to people, because maybe there is just a misunderstanding.

I always order caramel coffee without caramel sauce because the sauce has milk in it but the flavor doesn't. Most of the baristas tend to be confused by this, too. It's annoying but you talk and explain and then you get what you want.