I find there's an asymmetry between listening and speaking. It's fine for someone else to tell me about their week, but I can't reciprocate with the same level of detail.
replyI suspect when driving demands attention, it's easier to buffer incoming words to handle a second later, or to simply miss portions and recover.
In contrast, a buffer of outgoing words between mind and mouth is harder to manage, and people prefer not to fall silent in awkward socially-unacceptable ways, especially if the other person might not see what diverted you.
Yes buffering / dropping on buffer overload is the right frame and the right way to do it in practice. I have seen it done properly. Yes it can cause some social friction but as long as your conversation partner is aware that because you are driving you may buffer/drop conversation packets and they accept that they might have to occasionally exercise patience or repeat themselves then it's fine.
replyDaydreaming or zoning out while driving is reckless behavior. You should be fully occupied by the task at hand. If you aren't, find a parking lot to doze off in instead please, or call an Uber
reply> In my experience the driving-behavior part of my brain can run virtually autonomously
replyIt can, but I've heard quite plausible claims in the past [1] that you shouldn't let it - because that's one of the things that kills motorcyclists. Your autopilot brain is looking out for other cars quite effectively - but a motorcycle isn't a car, and can slip through un-noticed if you're mind is engaged elsewhere.
[1] Citation needed, but lacking I'm afraid!