Indeed. This is one of the differences between the Unix and the MS/PC/DR-DOS command-line world. In the latter, recognizing empty final pathname components actually did become a way of differentiating such situations. I wrote a set of DOS and OS/2 tools in the 1990s, including COPY and MOVE commands, that had this very behaviour. I wasn't alone.
that's not a cp difference, cp is the granddaddy here
I think trailing / could be a nice way to indicate some meaningful difference, but since autocomplete always sticks it in, just feels like a bad idea to me. I might like it if directory names always had to have a trailing /, but I am less motivated by "convenience of common cases" and much more by "absolute precision/specificity/unambiguity" belt and suspenders.
(kind of unrelated but along the same lines, I toy with the idea of getting rid of . and .. visible in the filesystem, and make them only part of the syntax of paths. then you could have unambiguous multiple links to a directory: ".. is where you came from" and .. in the root is still the root, so chroot works too)