I find it hard to believe that someone actually mixes these unless they completely skipped all math classes in school.

Ah, yes the "I can't fit it to my mental model, therefore it is impossible" argument.

When little, my brother used to mix up the words "more" and "less" while speaking. I don't doubt someone could mix up > and <.

It's easy. They're alligator mouths, that always go for the larger number (greedy alligators!)...

This genuinely confused me because I thought the larger number would eat the smaller number.

The alligator is just the symbol, ignoring the smaller number completely.

I used to mix it up in elementary school because the school teacher explained that "<" is "less" and ">" is "more". Even worse, she suggested to memorize it like this: |<leiner = kleiner (german, meaning less)

At some point I realized it's possible to memorize it visually, since then I never mixed it up again

Yeah people frequently mix up left and right also. And my brother always wrote his numbers backwards or rather left to right (units on the left).

I remember several kids in my class having great difficulty with < and > when they were first introduced. I can well imagine many of them just decided it was impossible and gave up.

Was it possible to give up? In my place, they wouldn't be let on to the next grade if they'd fail basic math - i.e., they'd spend the summer repeating it + an extra year in the same grade if that wasn't enough; so it would have to be a real exception to see a 10 year old who can't somehow manage that.

Anyways, the classic mnemonic for that was simple - for < and > the wide part contains more 'thingies' than the narrow part. They're actually taught before numbers or together with numbers, like [pic of four strawberries] > [pic of three strawberries].

I was taught the crocodile thing, but had real issues with it: I can think it through but it's not fast. I'm pretty much ambidexterous (i.e. write with left and catch a ball with my right) so while I can do quite a lot of things with both hands I also have problems with left and right!