Also I don't like it as an internship program. Interns generally do useful work, their internship project is something that the hosting team needs. STEP interns generally don't, their project is educational (that is, won't be used), and the internship involves a lot more lectures (as in, sitting in a conference room and listening to somebody). It's good for some people I guess but if you wanted to "work at Google", STEP isn't it. It is a foot in the door towards getting in as a regular intern next year, though, so if you're OK with wasting a summer then it's a good option.
Oh, one more thing -- interns are currently enrolled in a university (which explains the ages).
I got that from this wonderful book, btw: https://www.amazon.com/Supermen-Seymour-Technical-Wizards-Su...
I mentioned 1951 because organizations were so much less flexible back then, making the example more compelling. I was going to say that, but then I remembered that in the book it talks about how the engineers at that company would bring their dogs to work, so it was obviously atypical.