Gien that normal wall sockets in Germany are 230 V 16 amps... including the 80% derating factor for continuous loads... that's about "10 miles per hour" of charging for a Model 3. 10 hours of overnight charging would get you about 100 miles. Some people would want faster charging, but that would be plenty for a lot of people. Could install a couple of heavier circuits.
The main issue appears to be the apartment builder's assumption that everyone would be using all the sockets at max rate all the time, which is not realistic. While it is certainly possible to buy enough electric service to cover that use case (as I demonstrated), it would make more sense to make rational assumptions regarding customer usage, and have load balancers so that everyone could plug in, but the rates of charging would drop if everyone was pulling power at once. I mean, even Tesla does this with its Superchargers. Most of the time, most people will be drawing nothing -- either their car is being driven, or their batteries will already be full, So only a few people will be pulling full power. Occasionally lots of people will be plugged in, and they can all have lower rates of charging until some of them fill up.
This solution is actually commercially available as an off-the-shelf product (called ‘ChargingPlaza’) in Germany (and Benelux): Charging solutions - Smart charging - Allego. The first installations in Belgium were done in october 2017: Intervest krijgt eerste laadpleinen.