I agree that this would be a cautious approach, although I know quite a few people who have over 100,000 miles on their auto transmissions without any signs of issues. My son changed had his 2012 Mazda 3 transmission fluid changed at 100,000 miles. It had never and is not now having any problems.
Our 19.5 year-old RX400h now has over 140,000 miles on it. The service booklet recommends changing the transmission fluid only if the vehicle is regularly driven in the desert, dirt roads, and/or to tow a trailer (up to 3500 lbs), I believe. Most likely, we have already had the fluid changed at least once.
Of all the auto manufacturers, I would say that Toyota/Lexus is the least likely to engineer their vehicles to fail after the warranty expires if no maintenance schedule for a fluid change is listed.