I like the distributed spirit of this, but it only works where there is another layer holding the ISPs accountable - whether it's other ISPs or a government body. Right now their incentives are only to satisfy customers' perceived needs, which leaves nobody incentivized to prevent endpoint-to-endpoint harm.

But the ISPs are not held responsible. They can externalize costs to society, and so they do so - because that is what capitalism mandates. Without an institution that puts those costs back where they belong, nothing will change, because it is cheaper not to change.

I'd recommend reading up on the Cuyahoga River, the Clean Water Act, and the formation of the EPA - it's pretty much the same problem. Industry creating problems by abdicating its responsibility, necessitating a legal solution. And enforcing that requires a public institution.

Charge per device access? And those devices need certificates of worthiness similar to cars MOT certificates (UK example)

An interesting idea.

What is the minimum viable "superhighway-fitness" of a device?