This sounds like a cynical take on their motives but is actually just buying into the narrative the ISPs have pushed that these caps are because the bits are limited and caps introduce fairness.
https://arstechnica.com/tech-policy/2018/06/comcast-says-it-...
In actuality Comcast has outright said it's a business decision, not a technological one, and at&t said uverse had no need for caps unlike their old dsl network and then added them anyways.
It's rent seeking, plain and simple. The exact same way that the extra cable fees go up multiple times a year outside the advertised contract price and uncorrelated with inflation, government requirements or broadcast carriage fees.
And then they spin it as fairness for the heaviest users to pay more and justify it as only 1 in 20 people have to pay it anyways, so, hey, don't worry about it.