We had a long discussion about the issue of OTAs that potentially reduce functionality in this thread:
They said "you can't stay on 7.0 forever. .."
About the legal aspects, later in the thread there is a discussion about EULAs and whether Tesla needs them. Other software updates in general do not warn about possible issues or reduced functionality it will cause, but inside that thread it was argued that EULAs are what allow that to happen.
As for examples from windows, look at the whole Windows 10 update fiasco. Microsoft resorted to malware-like tactics to force people to upgrade from Windows 7/8 (including automatically updating). However, Windows 10 was buggy and does not work with some software that Windows 7/8 supported.
About Apple, just google "ios slow". There have been plenty of examples where new versions of IOS slow older devices to a crawl. If you just updated when the new version was out only a few days, it's possible to still downgrade back to an older version. However, older versions are marked invalid after a few days, so there is a limited time window that if passed leaves you only with the option of buying a new device or dealing with a drastically slower one.