This is because, when an operator doesn't have direct coverage but can use the networks of other operators, the cost is higher. Orange has agreements to access Movistar's fiber network in Spain, but depending on whether the municipality is competitive or not, this access may be different. For example, if the municipality is non-competitive, Telefónica is obliged to allow access to other operators, whether or not it has an agreement with them.

Operators pay others to access their networks

This means that operators have to pay a minimum to Movistar to use its network, with a cost that is currently around 17 euros. To this must be added other costs, such as the network capacity that they contract from the operator to provide service to their users.

This is the reason why, even if you have fiber coverage with an operator, you may not be able to contract the best available offer, since that is only available for direct coverage. If a fiber rate is offered for less than 20 euros over indirect fiber, then the operators would be incurring losses.

The contracting of capacity is another very important factor for which it is always advisable to contract a fiber rate with an operator that offers us direct fiber. We see an example with Digi, which has constant speed problems at peak hours, as users report almost every day on Twitter. This is due to the fact that Digi contracts little capacity from Movistar in order to save costs. With a direct connection, it is almost impossible that you are going to run into these speed problems, and sometimes it may pay a little more to make sure that you always have the maximum speed available.

Link: https://www.adslzone.net/noticias/operadores/fibra-optica-directa-mejor-contratar/