There is zero "per-bit" cost for data transmission. The cost of a circuit is all physical plant. That is, the _actual_ cost is installation and maintenance and right-of-way and rent. All of which are dependent entirely on real wall-clock time. Metering something with a natural maximum capacity and no unit cost is the stupidest model _possible_.
When the various people decided to put a price on the data itself they created a bottomlessly hungry monster. That monster was the total cost of all the peering agreements that _also_ put a price on the data itself and a race between all the providers trying to claim their receptiveness was more valuable than their transmission burden.
So the current market is _boned_ because it isn't driven by any market force except greed.
In a rational world I could sell you an unlimited link to my backbone at a known fixed speed, with the understanding that your effective throughpt and potential delay to any destination is simply not something I can control.
Then the market force would be "Provider X is too congested, I'll switch to provider Y". The cost of the link and the speed of your first/last mile, and your best bet for a good provider with a good backbone would be your selling points.
So the problem with the internet here in 'merica is that it's become a Libertarian Ideal Toll Road... Its clogged up, over priced, full of unmet promises, and barely functional. People are all trying to over-burden "the best" roads because the normal roads have all fallen to shit. The service providers have had to limit the hell out of their points of connection because each one is metered so the mesh has become a set of inter-linked long-armed stars where my transmission of a packet to a business down the block may pass through several of these united states.
If the costs weren't inflated by the per-bit pricing and predatory nonsense then the connections between networks wold be much more open. People wouldn't be worrying about "who's data is on my network" and most routes would be much more direct. Each provider would see user uptick as a opportunity to shorten their net spans instead of a call to throttle their nets. The best networks would promise not a speed in megabits but shortest transit time off their net. Bulk providers (Goggle and Youtube, vs Netflix, etc) would be invited to make as many close-end and colocated insertion/service points as they could muster.
An "unmetered" internet just works. Ask most of the rest of the world. You pay to connect. You take your chances for throughput. And all the effort and human and monetary expense is spent to get your data to its destination by the best route possible. Then Open Shortest Route does the work so you don't have to.
NOTE: This doesn't hold for "unlimited data storage for free" models. It's _incorrect_ to conflate transit and storage, everything is completely different for storage. That's the difference between being able to use a road and needing to build bigger warehouses.