Kick down should drop a gear to increase engine rpm. Unless you have a ford escape with a six speed auto... that thing shifts up and down a couple gears at a time for some crazy reason... but tbh does what it needs to do.
I loaded an orange semi with long logs and drove it up and down the ridge a few times on the road. The transmission does drop down to 1st a lot when it could have just shifted earlier to a lower gear. Once i noticed it dropped into 1st and immediately shifted up through 2nd to third...
I get that it bothers you though. Maybe mudrunner 2045 will have some kind of infinitely variable laserdrive.