They may think disclosing the specific updates doesn’t matter to the average user. I think they are probably right about this. 
 

The Apple iOS App Store must send me half a dozen various App updates most days and their notes often say ‘bug fixes’, ‘enhancements’, improvements’ or ‘security updates’ …and the such like.

I don’t personally expect to get too much info. about the security updates and I don’t really need to know about things like a ‘comma’ missing in a line of code etc. I just want to know when new things appear in the App, or have been removed from the software. In fairness I think Sonos do that - their public list of software changes during updates are shown here:

https://support.sonos.com/en-us/article/release-notes-for-sonos-s2

Those release notes are enough to satisfy my own needs - I don’t want to be bombarded with all the technical detail.

I don’t suppose your ISP tells you anything much about your regular router maintenance updates either, assuming your router is ISP-supplied. 

For example, after the last updates the bass, treble and balance sliders on the equalizer now works correctly, the equalizer is adjusted live when you adjust the slider and not as before where the adjustment first occurred when you removed your finger from the screen.

And I've noticed another good change on my Port that I don't want to mention here because I don't want to start a long discussion, because most people won't notice it.

Sonos updates are pretty invisible here, usually see them mentioned on the forums before I notice them on my system.

Once is set static/reserved IP addresses I just set things to update automatically and ignore the whole process.

My current Linux systems seems to be averaging 50 updates a day, makes Sonos look like pikers.