For most utilities (water, electricity), there’s a relatively linear relationship between the tangible value provided (energy used, water dispensed) and the cost to provide it (coal burned, water sourced/treated). Even for wind- or hydro-powered electricity, the amount that everybody uses has a proportional amount of wear on the system and consequent required maintenance.

But not so much for ISPs. Instead, you’re basically paying for a “fictional” amount (speed) of a non-tangible product. Granted, there is a linear relationship to the amount of electricity the ISP uses to provide each bit, but it’s negligible.

Instead, what you’re paying for with internet is essentially to recoup the fixed costs of the provider’s equipment. They do need to upgrade every so often to accommodate more capacity and faster speeds, but this is proportional to speeds provided and not data volume used.