I thought so too, which is why I never posted a question here. But due to the broken door handle, I asked them to look at it (not replace it, just to find it if it's normal), since it's very intermittent I was sure they'd tell me "it's fine" or "we can't find it". 98% of the time it worked perfectly, but the other 2% I'd need to keep scrolling to get the volume to react. Once it reacted, the button worked again for a while.
This is the repair memo "verified the volume control intermittently inop, performed diag, and found the thumb screw switch faulty. replaced thumb screw switch and rechecked for proper operation."
So far (4? days since I got my car back), it's been 100% working.
My other
scroll wheel never lagged (or was unresponsive), so I wasn't sure if it's software lagging on the volume or hardware. Turns out to be hardware. [I also rarely use the right scroll wheel, only when looking through my recent calls or opening pano]
