The primary purpose of an internship at most major companies is hiring - you can screen candidates much better before extending a full time offer and the candid

The primary purpose of an internship at most major companies is hiring - you can screen candidates much better before extending a full time offer and the candidates can also get a better read on how much they'd enjoy working there. Even the second order effect of drumming up hype for others to want to work there is probably more important to many internship programs than whatever the interns might tangibly produce. At least I can say for sure that people at Google aren't shy about how it takes a few months to get up to speed with internal tooling and not much is actually expected from a summer intern. But they built themselves into a brand on campuses, which became so mainstream there was a stupid movie made about how fun it is supposed to be to intern at Google. And as far as finance goes, trading interns aren't even legally allowed to trade, so I wouldn't be surprised if the culture surrounding internship at Jane Street just leans more heavily into this for SWEs as well.