I've still encountered text on the Internet that substitutes I for 1 and O for 0, presumably written by people who learned in an earlier era and haven't shaken that habit.
But it's slightly hard to search for because a lot of the search results are OCR errors. Still, I'm sure not all of them are because I've seen this in newly-published news articles (maybe written by journalists or edited by editors who've been in the news business for some decades?).
In old-style figures, 1 only goes up the x-height, so that wouldn't work. But even in "typewriter" typefaces on computers, 1 and l (el, not eye) look pretty close. And the difference between O and 0 is mostly the width, which is fixed on a typewriter anyway.
Sections 2 and 3 contain the most readable man pages out there. The pages in sections 1 and 8 are often terrible, being the result of some texinfo->man filter.
Zmodem's code is uglier than Kermit's IMO. Gods help you if you have to read either, but Kermit is written better and EK is almost understandable once you fold all unneeded #define's.
I'm surprised no-one mentioned the venerable UUCP. It has more variants than X/Y/Zmodem combined: at least 12.
The only upside of this is unbrickability. Having the boot ROM inside the CPU means you are stuck forever with whatever bugs there are in it. Been there.