Bitmain didn't come up with Bitcoin cash until months after this specification was done, and didn't make the name public until even later... if there was any intention of confusion there it could only have been on the part of bitmain and their contractors.  Similarly, B2X named themselves BTC1 long after.  Unfortunately we cant do anything about altcoins using intentionally confusing names and labels.

Last character of the HRP has to be completely out of the data charset. making it all case sensitive would reintroduce the mixed case errors (though not as bad if it was only the first chars, but just as you complained: special rules don't help the users if they don't know them)... and then you can't do things like have it optionally in all caps which is nice in some contexts, and can be pretty visually attractive too.

Yes, there certainly was that effect, I was really kind of gut punched by your post and was sort of thinking you'd turned into a bcash shill -- acknowledging it absolves it.  I'm sorry for being a bit quick to judge there. Don't be a stranger.