Lobbying aka bribery.

My city (Longmont Colorado, US) fought the giant telcoms+cable and won two separate battles, although it cost us a decade when we could have had cheap fiber available. As it stands we still have one of the fastest internet services with high-quality gigabit speeds coming straight into our homes. What's more, we typically have same-day repairs for most connection issues. I've never seen an interruption here in the past 8 years, but I know one part of town had a hub taken out by falling trees and it took them two days to get people reconnected, while the cable service took 2 weeks to get people running again.

We don't have free broadband here, but it is still considered a required service by our city government, much like power and water, and they take problems seriously. The service has been so successful that residents of nearby cities have been hammering their own city governments, publicly shaming them for taking bribes from cable to actively prevent getting quality service in their areas. Slowly but surely the bar is moving, and some of them are finally getting connected too. It just takes one good example to show people what they're missing out on, and then they start making changes happen.

Greed.

The answer is always Greed.

What profit is my government(Greek) going to have by doing this? Nothing, so obviously it's not gonna be done.

If everything is because of profit, then nothing works.

We had a guy who tried to do this in the UK. Everyone voted for boris though cuz brexit