I'd like to think that programmers back then most likely "graduated" from using punch cards, hence they have a higher mental guard against typos and mistakes wh

I'd like to think that programmers back then most likely "graduated" from using punch cards, hence they have a higher mental guard against typos and mistakes when writing their program (or essays), compared to programmers that grow up with unlimited undo/redo. Back then if you had a typo you'd most likely have to wait overnight, or even days to get the notice so you spend a lot of time proofreading your text, and over time it becomes a second nature to write something right (most of the time).