Would the consumer be responsible for paying for: -DDOS (not only can you knock them offline, you can cost them big money) -Spam (Both received and botnet sent) -Retransmissions for traffic the ISP dropped due to congestion -Ads (adblockers could reduce bandwidth costs by a third)
I personally would love volume pricing. But I also would not want to provide tech support next time my parents get hit by malware and get hit with a $1000 isp bill.
It's the incentive that's lacking at the moment. My machine may send out bursts of spam at 3am, or a website ad may weigh 10MB, but as long as I can still check Facebook what do I care? But I would care if I were billed for those transfers. I'd start shopping for devices that helped me self-throttle. I'd start caring whether websites were bloated. That would pass the incentive on to those providers, etc.
I get that once the traffic hits the broader 'net that all bets are off. That's true and nothing can be done about it.
But in this case the ISPs aren't even making a "best effort" on their own network. They're deliberately not upgrading congested links where their peering counterparties are willing to upgrade. That is not a "best effort" class of service.