> I think all programmers expect that if x == y, then they refer to the same file. This is not true currently.

Perhaps, but you could equally say that they expect that if x != y then they refer to different files, which is also not true. So do we optimise for the false positive or the false negative? It really depends on what operation you are doing, and so it has to be left in the hands of the developer.

Currently, we have a cheap comparison that minimises both without preventing either. The only option for PureWindowsPath is to prevent false positives (== always means same file), at the cost of causing so many false negatives that I suspect most developers would simply roll their own equality comparison. That's not the status quo, and especially for a behaviour that has been shipping for a few years without significant problems, changing the status quo that dramatically requires a more compelling case than has been presented so far.

If there are ways we can reduce the false positives without increasing the false negatives, then let's do it. But pragmatically, we should balance both, and leave the "perfect" comparisons to other methods.