Yep, there is a drain plug on the bottom and a fill plug on the front of the transmission. If they required some weird proprietarty tool or were one-way heads I'd say the transmission was sealed, or at least that Mazda only wanted their technicians working on it. But the plugs are regular hex plugs so anyone with basic hand tools can check or change the fluid.

Mazda does spec a very common type of transmission fluid in the owner's manual too, which is a tacit acknowledgement they expect it to be checked and changed or topped up at some time.

Anyhoo, at 80,000+ km it won't hurt to have the fluid changed. It is a maintenance procedure, not a repair so you shouldn't notice any huge difference. If synthetic fluid is used then shifting will probably feel a bit smoother, especially on cold days but that is probably the biggest change you should notice.