One surprising thing I've discovered, as an adult, is that most people never really learn to write or read very well. Their having obtained a degree usually doesn't even change the odds that much. As a kid, I'd never have guessed that was the case.

I don't know whether this has been the case forever, or if it's a new development—I mean, I know widespread literacy wasn't the norm for much of history, but what about after compulsory education became A Thing? A typical letter home from the US civil war or even WWII, from conscripts, not officers, seems to be hyper-literate compared to modern norms, but that may be selection bias (who wants to read the ones that aren't good? Perhaps my perception of "typical" is skewed)