In reality residential US ISPs don't really care if their users are getting a sub-par experience since they're often the only fast/fiber provider in the area of their customers, meaning customers have no way to switch. Plus, when a website doesn't work, unless the page itself calls out the ISP (which they never do), customers will think it's an issue with the website and won't possibly attribute blame to their ISP until they're deep in forum threads with people telling them "it's probably your ISP not doing anything about bad customers" - the amount of users going so far to learn this information, then accepting it, is extremely low.