Yes, the comic assumes people struggle with order of operations.

And this is why I said, "did nobody learn order of operations?"

How did you instantly know that the character struggled with it? Because you thought that order of operations is something many people struggle with, so it was the first thing you checked. Imagine an alternative:

12 ÷ 2 = 3!

"Ah, you forgot that ÷ 2 does not mean dividing twice" -- this is just not a mistake you'd think somebody would make, so it's not funny. If this were the comic, I would just say, "did nobody learn how division works?"