In some countries there is sometimes a cable & data connection owner and then a separate service provider. Laws regulate that the cable provider must let other companies provide connections to customers over their cables. The service provider pays the cable owner for a bulk of data that its customers use. The cable owner can't charge more than it charges itself when it acts as a service provider.

Not sure if that made sense! I pay company B but my fibre connection is provided by Company A. If I want to change to Company C I start a contract with C and the only thing I change is the cable modem.