One cannot be sure that some residents are only looking to find a cheap house and do not intend to obey the regulations. It remains to be seen if social pressure can regulate the behaviour of the neighbourhood or if the administration will have to prosecute illegal parking with fines up to 50,000 Euro . But large scale violations are very unlikely. The attractiveness of owning a car decreases the further the car is parked away from the apartment. Because there won't be public parking space in the district, cars would have to be left in the next district.
Most residents are unlikely to find that attractive.
The aim of the policy is a flexible solution. Different types of living area within a district should generally be possible. In every city there should be the opportunity to live in a car-free area for those who want it. And, as this example shows, it is possible to agree an exemption to the building regulations. But such changes often require the initiative of residents together with some perseverance.