It's not hard. While some of the folks I taught this basic math to were just plain dumb, most turned out to be capable, hard workers.

I think it's more a reflection of growing up in extreme poverty, in a broken home, young gang activity or childhood immigrants that had to learn English and everything else in school.

One dude I taught fractions to was this beast of a man who just got released from several years for selling crack. This dude could pick up and carry 2 full size oxygen bottles across the yard like nothing.

He learned quickly and was super willing to work his way up. He grew up selling drugs, skipping school was in a gang as a kid and only had his mom who could barely put food on the table when he was a kid. He told me he was bullied in school for showing up in old clothes and ragged shoes and wasn't till he started selling drugs as a kid that he first could afford a nice pair of sneakers.

He eventually got picked up for selling coke one weekend, but he was a hell of a shop hand while we had him.