104 key mechanical keyboards have 104 buttons and may go for $30. Maybe it is the knobs? But you can get a midi keyboard with 8 knobs, 49 keys, 12 pressure sensitive pads for ~$100 (but maybe it wouldn't last in car cabin heat).

Those keyboards don't have the same environmental requirements. Automotive environmental is hard. Temperature extremes, high and low, plus humidity extremes.

There are also reliability expectations. If I need defrost because the windshield just fogged over, it better activate when I turn that knob on my sixteen year old car. And so far, it always has.

Can it work at -40 C or 85 C ? Can it work after it was in a salted atmosphere for 100 hours ? And then in a sandy atmosphere for 100 hours ?

You can get an in-dash CD player with 2 knobs and 10 buttons for $45 or something, and it stands up to cabin temperature and humidity cycles.

Okay, remind me to never leave a keyboard in a front seat of a car, apparently it can't survive in there.