Not necessarily; you can do a thing where it's randomized during development, testing and fuzzing but not in production builds or benchmarks so that the obvious "I rely on internal map order" bugs are spotted right away.

You can get it pretty much for free by using a random salt with your hash function. This is also useful for avoiding DOS attacks using deliberate hash collisions to trigger quadratic behavior in your hash tables.

Any sane language would design a list iterator to follow the order of the list. No, the difference is when you're iterating over orderless hash-based sets or maps/dictionaries. Many languages choose to leave the iteration order undefined. I think Python did that up to a point, but afterward they defined dictionaries (but not sets) to be iterated over in the order that keys were added. Also, some languages intentionally randomize the order per program run, to avoid things like users intentionally stuffing hash tables with colliding keys.