Protip: The government, yes any level of government, is 100% able to build affordable rental units at whatever scale it likes so that all of us can benefit from the kind of cost of living Vienna has.
Protip 2: The reason the government does every other scheme you can think of is because they are the landlord class, and represent the wealthy, so they want to do whatever drives up the cost of living while saying, out loud, they are doing the opposite of deliberately driving up the cost of living.