I've yet to find anyone who hasn't written part of a CAS that understands what algebraic manipulation even is, let alone how to do it outside of hand picked artificial examples.
I find it astonishing that term rewriting systems are considered esoteric mathematics that you don't see unless you work in a very specific and niche fields of mathematics or computer science.
Much less than 98% would fail that, why do you think that? Do you really believe that almost all STEM college students are that dumb?
Likely you misunderstood something here, not the people you talked to. Do you mean they get confused with that notation? Not understanding specific notation doesn't mean you can't do the thing.
I find it astonishing that term rewriting systems are considered esoteric mathematics that you don't see unless you work in a very specific and niche fields of mathematics or computer science.