Those who drive manual cars are frequently removing a hand from the wheel to adjust an aspect of the car without looking and I would be surprised if the momentary loss of a hand on the wheel would mean manual drivers had more accidents than automatic drivers.

Re: steering wheel buttons in general, it depends on how they're implemented. If you take an old idea [1] and provide tactile locating then it is easy to learn. If you can reuse a common paradigm (a knob for volume) there's no learning required. The steering wheel also is already a busy place - you have two or more stalks nearby, sometimes cruise control is part of the steering wheel buttons and even if not the amount of space means you are forced to provide a subset of functions. A stereo with tactile-marked buttons and knobs is known to most drivers via other paradigms and is easy to swap between cars.

[1]: https://patents.google.com/patent/US2350059A/en

There's really no need for more than one hand on the wheel unless you're turning, in which case you shouldn't be using radio controls anyway.

Just don't ever: grow old, break an arm/hand, become disabled, get weakened by illness, or be born a smaller person. Then yes, you'll always have an extra hand for off-wheek controls.

I'm a short guy who has driven my manual car while my right hand was basically a stump from having a knife put through it and having it bandaged up. I did drive slower in general as I couldn't shift as fast and it hurt to do so using the stump, but otherwise I was fine with one hand on the wheel.

For everyone else, we've had automatic cars for forever. There's also a video online of a man with no arms who learned how to drive their car without them.

Edit: changed to be specific about the one hand on the wheel.

Applies to manuals too.

It take about 1.5 seconds to move the gear shift. You can wait that long before changing the radio station.

Downvoted because this doesn't address the underlying point: differently abled people are just as important. And if their needs can be met with so little extra effort then why push back so hard?

Consider that at a critical moment the difference between moving a thumb and moving ones whole arm and hand could be the difference between life and death.

EDIT: fixed typos

That is an odd reason to downvote considering the comment I replied to didn't mention that at all.

Fair enough. I thought it was replying to the comment by ellard.

Steering wheel controls are less cognitive load than fumbling on your dash, even if you keep your eyes on the road you're still distracted.