If I can't privately listen right now, I don't, and if they get annoyed, I'll tell them why.
If something would require me to replay it multiple times to take notes, depending on the situation I'll tell the sender to type it up.
It isn't a matter of trying to punish, it is negotiating preferences. Send me something I have to interact with, and it may well take me some time to get to it. This is no different than emailing me a PDF.
True, the latter is definitely a good change. I noticed it in work too, people don't call without asking first. It's really a great norm because you can say "just give me 5 minutes to complete this" when you're concentrating.
Of course it was never a norm before because text messaging didn't exist but it makes sense.
It would be great if people started doing that too for voice messages.
It's definitely a much worse experience for the recipient, I think new social norms of asking first are probably the best solution. I wouldn't ring someone who wasn't expecting a call without asking them if they were free to call first for example, and I think the same should apply to voice messages.