It's honestly amazing that Excel hasn't fixed this issue. It's pisses off an enormous number of users especially in basically any non-US country (even if 01/02 is a date, it isn't the second of January in most of the world...)
Excel is stuck. It can't change this behavior if it cares about backwards compatibility. There are uncountably many recorded macros and all sorts of scripts and data tools everywhere, that implicitly and inadvertently depend on behavior like this. Like Javascript's warts, you have to declare these as features and live with them. Of course Microsoft has thought about this, it's silly to think they never have and we're…
that's a fairly sophisticated solution, but it's just one of many potential approaches to fixing the problem.