Well, it could buy them. If they had money left to spend. But Berlin pays for a lot of public services already because it is operated by politicians who cater to the same public that favors removing bill boards. As a result e.g. they just bought all privately operated power plants for billions. They also heavily subsidize public transport tickets because it is popular. And they employ a large public staff in the city‘s administration but still cannot maintain a good quality of service despite all the billions spent (you wait weeks for appointments).

Berlin is a text book example of how turning everything into public goods and spending a lot of tax money is not necessarily in the interest of the citizens IMHO.