That is a really good point and it complicates a lot of string-based questions, which is why they are almost always constrained (either implicitly or explicitly

That is a really good point and it complicates a lot of string-based questions, which is why they are almost always constrained (either implicitly or explicitly) by assuming that the string is ASCII only, which seems reasonable to me. There are probably better filter questions to use that don't require as many artificial constraints.