[throwaway201103]

> to build houses there is a need for a underlying infrastructure (roads, electric grids, gaz pipes, whatever...). Who's going to pay for all that

For a new development, the developers pay for it, either by actually installing the infrastructure themselves or by paying "connection fees" to the utilities to establish the service. For a truly "greenfield" development they also build the roads, which may stay private or be turned over to public ownership.

Ongoing, the gas/water/electric customers pay for maintenance as part of the cost of the service.

Where I live, the only utility persistently moaning about cost of maintenance and infrastructure is the water/sewer service, which is run by the city. Gas and electric are private utilities and they seem to just deal with it.