I agree it's disgusting that they do this retrospectively, people bought their 3 or 5 years reds ident in all good faith thinking they could come and go.
On the other hand if someone obtains residency then they are saying that's where they reside, and with that comes the ability to buy a car, have a phone line, get a museum pass , join the government health system etc etc
If they are living for a third of the year somewhere else, then they aren't really residents are they? And presumably they're using the services of the country they live in the rest of the time.
What they need to do is to have a visa system whereby people can come and go to the properties they've worked hard to have and wish to enjoy time in.
It's a crazy system.