But that's something different than what Cox is doing.

"Unlimited" and over-subscription aren't incompatible. You have a gigabit connection, the 40Gbps uplink is shared between 1000 other people who each have a gigabit connection, the over-subscription rate is 25:1. That's fine as long as the average usage during peak hours is 4% -- which it might very well be. A 4k Netflix stream is 25Mbps, which is 2.5% of a gigabit connection, so you're not above that even if everybody is streaming in 4k at once.

You're even fine if everybody is streaming in 4k at once and then on top of that 15 people want to fully max out their connections. And everybody using their connections at once doesn't really happen. At any given time a lot of people will be using zero.

Now, there will be times that are outliers. Maybe a popular video game drops without staggering the release and suddenly 30% of the customers are maxing out their connections at once to download an update and the average speed drops from 1000Mbps to 100Mbps for a couple hours. That's why it says "up to", right? That isn't artificially limiting anyone, that's just everyone getting their pro rata share in a time of atypical demand.

But on a typical day with an adequately provisioned network you should be able to get the speed on the label, and there is still no reason to be limiting anyone's speeds during times the network isn't over capacity.

The issue is they don't want to over-subscribe their network at only the ratio that would allow them to provide the rated speed on a typical day, they want to promise more than they can deliver and deflect blame onto people who are only using what they were promised.