This is the number one problem I have with automatics!
Even in 'eco' mode, most tend to shift down. It seems completely wrong. It should just be in 'sports' mode that it always kicks down.
And I'm pretty sure I've driven an automatic car that had paddles to drive in manual mode but it STILL shifted down.
Also I assume your point doesn’t apply to diesels, and I’ve noticed the same shifting down in diesel autos.
and the point does apply to diesels, the same as it does to any engine with pistons and a crankshaft. it's just that the operating range of a diesel is a bit lower.
Except that I drove an auto for all but my first 3 years and last 3 years of driving.
Now I drive a Tesla and the janky auto transmissions and lag in an ICE for the engine to rev is so maddening I actively cringe just trying to drive a rental.
It's true that it takes less effort to drive. Easier to drive by just using one leg and easier to use one arm. But the loss of control is real, at least for me.
One example is moving from zero to non-zero. If I just release the break while standing still, the car slowly accelerates, too slowly. If I gently press the accelerator pedal, same problem. If I press is slightly more, the car accelerates too much. There doesn't seem to be a sweet-spot anywhere for a smooth but fast "takeoff", which is easy to achieve with my manual car.
Another example is highway driving and wanting to accelerate to pass someone. Sometimes the car decides that when I press the accelerator (while driving in 120km/h already), to shift down a gear to be able to speed up faster, but it's completely unnecessary, just go faster instead.
Last pet peeve is reversing. Instead of pressing the accelerator to go backwards, you release the brake pedal. But this again is hard to find a sweetspot and I end up doing stop-slow-stop-slow-stop... and so on, instead of just smoothly backwards without stopping, while being to adjust the speed.
Overall, I can't wait to get back to my car with manual transmission, so I can have a smooth driving experience again.