I realize that you chose one example off the top of your head, but it seems like an incredibly rare case. The majority of developers can understand "Queries involving this column are slow, it needs an index". Slightly more sophisticated developers can use an EXPLAIN statement (or it's equivalent) to see how many rows are being scanned and apply indexes where necessary. How many hours of coursework is it worth to obtain the knowledge "finding things in a ordered tree data structure are way faster than scanning through the whole table"?

I'm not sure if I've ever run into anyone who said "The things I learned in college have turned out to be pretty much worthless in my professional career. I wasted a lot of time learning irrelevant information." It's interesting that the majority of every CS education is always valuable, to every person, with no exceptions.