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.
The Turris Omnia is an open, powerful router that comes with OpenWRT.
Turris adds an additional UI and features beyond that, but the OpenWRT UI is still available and the stock firmware can be completely replaced with OpenWRT if so desired.
It’s a bit pricey but has great specs (1.6 GHz dual core, 2GB RAM, 8GB eMMC) and is an excellent device for tinkerers with headers exposing UART, JTAG, GPIO, and more. It has three internal mPCIe ports as well.
I am not affiliated with Turris but just happened to stumble upon a new one at a garage sale a couple of days ago. Lucky find and I’m excited.