Why not? Any decent CS course covers garbage collectors. It should be a matter of presenting a known algorithm in pseudocode. Unless they expect the whiteboard code to compile and produce a fully working garbage collector.
In the required core? I'm not so sure that's true. The concept of garbage collection, yes. But garbage collection algorithms would usually be presented in courses like PL or maybe compilers, that are often in the "take 2 of 5" list or maybe even in pure electives. (This is true of a lot of "important" CS "core" algorithms and concepts---every CS department includes them in offered courses but the requirements are usually structured so that not all CS majors will be required to take them.)
It was certainly true of the CS course I did in the 80s - as part of the second year (of four) Data Structures and Algorithms course we spent a lot of time looking at memory allocation and garbage collection. This was a compulsory course - even those folks doing joint degrees had to do it.
I'd be amazed if a CS course didn't cover this kind of stuff.
Well, it's hard to argue against your 25-year-old personal experience and your amazement.
Less snarkily: I teach university-level CS, and of the five schools I've had direct involvement with (as student or faculty), all covered GC algorithms someplace but I think at least four of them, maybe all five, had at least one path through the major that would avoid covering them. I have researched the situation for certain "core" topics other than GC at dozens of top CS schools and I can promise you that there are many topics that are widely (and correctly) viewed as very important to CS but are not required even at many of the best schools.
My comment was intended to demonstrate that 25 odd years ago these things were covered in a non-optional way when the were regarded as fairly esoteric. Today when a lot of mainstream languages have them you'd think a CS course would cover them!
Note I'm in the UK and degree courses here are, as far as I can tell, structured rather differently to those in the US. When I did a CS course the classes required were 80% fixed by your choice of course - there was no flexibility or modularity in the first 3 years, with only the final year allowing for selection of classes. There was no way to graduate without passing the class that included GC algorithms.
Of course, it wouldn't surprise me if this kind of approach has been made more "flexible" to make courses more "accessible".
We didn't have it covered in our CS program. We were taught the concept (keeping track of pointers to allocated memory, etc), but not the implementation part. Garbage collectors are pretty damn complex.
