This is called scheefwonen – which roughly translates to "crooked living" – and has been a point of attention for several decades at least, more or less as long as I can remember.
It's a bit of a difficult problem, because you don't really want to kick people out of their house just because they have a better-paying job, and especially in the current climate these people don't really have anywhere to go; €7k people will probably manage, but €4k/month will have a harder time finding something affordable.
I agree that evictions is an extreme measure and to be used as a last resort. I think it should be part of the policy instruments to be used, under the right circumstances. e.g. if you make 1.5x the wage that would give you a right to a social home, averaged over 3 years, then you get a 2 year period to move out.
That means you won't move out until 5 years after you've started earning more, and if your earnings were temporarily high, you get to stay. But if you're consistently earning a ton, you have to leave.
That's not so crazy considering that there's people who're low-income on a 10y waiting list for the home you'd be occupying, there has to be a mechanism that makes you have to leave. Yes it's hard to find something great at 3-4k, but it's even harder for someone at 2k who's 'spot' you're occupying. That could be limited to 5 years.
Everyone has a hard time finding a place, but why are some rich getting subsidised indefinitely at the expense of some poor?
But apart from evictions, I've never understood why we can't simply have dynamic rental rates adjusted to the market rate. I know people who live in Zuid for 500 a month in a home that's 1500 market rate, and their household income is 3x the average. Why can they not be made to pay 1500 to the social housing association? When they move out, the home reverts back to the subsidised rate for a low-income family.
I understand this can't be done on old contracts with no contractual clauses that make this possible, contracts are contracts after all. But we've had this situation for many years, and new contracts still allow the possibility of consequence-free scheefwonen. That's pretty absurd to me.
It's a bit of a difficult problem, because you don't really want to kick people out of their house just because they have a better-paying job, and especially in the current climate these people don't really have anywhere to go; €7k people will probably manage, but €4k/month will have a harder time finding something affordable.