Do you think measuring the temp then waiting for a trickle of fluid to pour out of the trans is more accurate than measuring what came out of the trans when you pulled the drain plug? I kinda don’t.
I read the service procedure at one point on Toyota’s with no dipstick. Honestly, it seemed like it had some judgement calls in there regarding exactly how much fluid was supposed to come out of that check plug at the proper temp and I’d trust myself measuring the old fluid more than I would trust an unknown tech following the procedure and getting it right. That’s just me, my personal confidence in my DIY skills and personal attention to detail border-lining on anal, and my past experience with letting someone else work on my cars.
As far as why they make it difficult, I have no idea. It seems to me that the most straightforward way of checking the fluid, even with a dipstick, would be to check the level cold with the engine off. But, no. You need to check it hot in park in a GM, hot in neutral (if I remember) in a Dodge because the pump doesn’t operate in park. Would be just as easy to mark the dipstick at the corresponding cold in park level, unless I’m missing something. And then you’ve got the whole no dipstick thing, probably because most buyers of new vehicles never check it anyway. They just trade it off at or before 100k miles.
Our (or my wife’s I guess, since I titled it to her) Toyota has a dipstick (thank goodness) that is marked “sealed for life”