Hmmmm.....
89 Aerostar....
MY '94 AWD Aerostar now has 135,000 miles with NO ATF drain/refill/flush only band adjustment at 125,000. My son's '94 AWD Aerostar only has about 70,000 miles but also never with any ATF drain/refill/flush. Would have to check to be sure, but like my '01 AWD RX300 I would guess that no ATF "maintenance is called for in the owners manual.
Yours..??
"...evident by the number of tranny shops...."
Has it not occurred to you that with the number of "trannys" out there the "bread and butter" for all those shops just might be from overhauls due to ordinary wear..??
My 89 Aerostar is on its 3rd transmission at 180,000 miles. I always had a drain and fill, and filter change every 30k mi.. That vehicle is a piece of crap compared to an RX. I think I've replaced about everything on that van at least once. As far as the tranny shops in my city go, I sure see a lot of newer vehicles sitting in the parking lot every time I drive by. It's a fact that most people don't have their transmissions serviced until they fail. A lot of people don't have their cars serviced at all until something goes wrong. My wife's car would have exploded by now if it wasn't for me taking care of it for her. I'm sure you guys know that story all too well.