I'd wager the bar wasn't as high back then as you think. Most people still wrote inefficient things. Lots of it.Lots of those people who wrote inefficient things were the C students in Comp Sci. A lot of those people writing bad code were home-grown programmers who were completely missing pieces of knowledge. From what I saw as an undergrad, it wasn't the 3.75 GPA CS students who were doing those things.
So, seriously, do you have data showing that the bar is lower?
It's not my job to do such studies, however I do interview job applicants. A disturbingly large number of applicants, who all have 3.75+ GPAs, try to tell me nonsense, like "null pointers take up no data." I'd say I encounter something about as egregious as that with a bit short of half. In my recollections of interactions with classmates, I could take it for granted that CS students who made it past Freshman year knew enough to actually implement algorithms and could actually implement a recursive function. If you had tried to talk to them about such things as some kind of deep esoteric knowledge, they would've just given you a funny look.