The reason is cost savings. It's cheaper to modify software UI than it is to modify hardware UI.
All of this leads to an increase in “failures” in seperate steps of the manufacturing pipeline, assembly of dashboard, assembly of car, after the car is completed, after it is shipped to dealer, and after the new owner picks it up, during the lifetime of the car. Each of those moments occurs a significantly increased cost of replacing the button.
By simply removing buttons and knobs, this source of failure rate goes down and it appears cheaper. It is also the reason behind going from 4 buttons for the windows to 3 (left, right, and a toggle for front/rear)
According to him the monetary savings were significant enough to proceed with it. Personally, I wish they wouldn’t. But I believed the numbers.
A button for a car is designed and tested to last 10 years. Software on the other hand...
All my cars have had basically the same controls for turn indicators, lights and wipers. The variations are minimal.
I got two cars with cruise control and I had to read the manual once per car (better not to experiment at high speed.) I probably just poked with the levers to understand how to control the radio. However it took me four years to finally make my phone play audio over Bluetooth (calls were OK.) Everybody's else phone was fine. I finally found the right incantation of taps on the touch screen. Luckily very few functionalities must be accessed via the touchscreen, most notably adjusting the time and resetting the tire pressure sensors.
> cheaper to modify software UI