When I was a student, I thought the same. Later when I designed some expression evaluators I've started to appreciate the language design (and hacks) required

When I was a student, I thought the same. Later when I designed some expression evaluators I've started to appreciate the language design (and hacks) required to make "100 - 5%" work "as expected" (that is, return 95). It's a pretty unusual grammar, and it is neat that it was implemented on something with only few dozens bytes of RAM.