The electric-car charging stations that I have seen at petrol stations elsewhere in Europe are not actually maintained by the petrol station. Rather, it appears that the petrol stations just allow charging-station brands to rent a portion of their plots of land to erect their infrastructure on. Consequently, requiring car charging at all petrol stations, instead of being a financial burden, may actually allow them to increase their income.
Also, since margins on petrol are so low, many petrol stations make their profit from their shops, not from the fuel itself. Since it takes some time for a car to charge, customers are likely to spend more time and therefore more money in the petrol station’s shop.