My wife's 2007 MDX has a AT filter that is supposedly a lifetime part. That filter is removed from INSIDE THE BELL HOUSING.... Trans has to be removed from the vehicle to change the filter..... Idk why manufacturers do things like that.The lower "TCO" on the first 100k miles is also true. It's not helped by vehicle designers that make the job of a fluid and filter change difficult (and thus expensive); I own a GM product where this is the case as they stuck the shift cable bracket bolts on TOP of the gearbox and your only options to remove the pan are to either remove that bracket or remove the exhaust cross-over pipe, which is far more trouble since the bolts holding that on at the headers are nearly-always near impossible to remove without destroying them or the studs due to the extreme heat cycling involved at that location. To add insult to injury to get to the bracket bolts you have to drop the front driveshaft. This turns what should be a one-hour job into a two+ hour one for absolutely no reason whatsoever; the bracket is in such a location that mounting it from the transmission pan bolts instead would have prevented this intentional "screw you" from GM.
BTW there is another reason on many ATXs to do this service regularly -- the valve body on many designs has a gasket that compresses with time. This in turn causes the bolts holding it on to not be at proper torque. These typically are threaded into aluminum and are low-torque but precision fasteners in terms of torque requirements. I frequently find them loose and that can cause fluid bypass, out-of-spec (low) line pressure and ultimately result in a catastrophic failure as well. If you never take the pan off you'll never detect or correct this condition with very expensive consequences.
Have you seen or heard of that type of valve body issues with these 3rd gen M6s?