Because electives frequently have nothing to do with your interest or future. I've had to take all kinda of nonsense over the years. Mummy science, music history (or some excrement) , us history, I can't even remember all the crap I've taken. But it had absolutely nothing to do with my interest (at the time) or career plans.
It makes perfect sense that a person would pay less attention that something that doesn't interest them, or that doesn't have a clear benefit to them in some way. I fully agree that it could be beneficial by teaching you other ways to think about it. But I think many people also think they would get a greater benefit from something at least tangently related.
If I wanna go into medicine how about a course on alternative medicine (something different, but related) instead of a art class.
Because it goes back to Pope's absolutely correct point that so many kids at 18 or 19 don't have a clue what they want to do, and quite understandably, so it make sense to do a bunch of things - many of which won't necessarily be that interesting or relevant to what they end up doing - in order to find the one or two things that really do flick their switch, and give them a focus and direction. Just because you knew what you wanted to do doesn't mean that others do, and it doesn't make them better off or worse than you. Just different.
And because it goes back to Alio's also absolutely correct point that even if you do end up following your chosen path you don't know what other apparently completely unconnected skills are going to come in useful in later life and in future roles, and just because Alio didn't pay attention in accounting and you didn't care about your electives doesn't mean that you won't need them in the future and regret not paying attention just like Alio, nor does it mean that others didn't pay attention and won't value them at some point in the future.
Education for education's sake is good. We need to stop tying everything that everyone does, especially kids in their late teens and early twenties, into hardline capitalistic values. Education in general makes people smarter, more inquisitive, more interesting and more rounded. It's a thing that as a society we should be encouraging and paying for.