Like if I want to tell my alexa to turn the temperature up on the thermastat I have to remember this exact phrase: Alexa, tell the ecobee to turn the temperature [up, down], [ecobee name]. Anything else and alexa tells me "ecobee doesn't support that". And alexa/siri/google are all top of the line, offline processing inside a car's CPU is measurably worse, and syntax is even more esoteric.
Ever try to use voice commands to tell your car to give you GPS directions to the nearest walmart? Basically impossible unless you have the street address memorized, and even then it's a 10 minute ordeal with a lot of stops and starts because the processor wasn't listening as soon as you started speaking to it so it only caught the end of an address, or it misheard a number or street name, etc.
Voice control is far from being an acceptable alternative to physical dials and switches.
1. Do not want to talk in the loud-clear voice needed for them to work (e.g. someone else in car is on their phone, kids are sleeping).
2. Completely soured on the experience due to things like this[1]
That said, people I know have a strange resistance to using voice commands with their cars and phones.