Don't forget the random charges for a few bucks that they stick on all the time banking on people not bothering to call and bitch about it because an hour on the phone isn't worth it for ~$5.
The reason their customer service sucks is that they see it as a cost they want to minimize, not a value add. Why do they want to eliminate cost? Because they are in a constant price war with competitors. Because we’ll switch if we can get $5 / month less. No one ever thinks twice about switching to get $5 / month less, and they they complain about bad customer service…
ISPs in the US are not in a price war with competition, that's ridiculous. The price per gig has been going down as infrastructure build out happens in the middle mile. In the last mile, prices are still abusively high with predatory bundling contracts. The reason their customer service sucks is because their customers don't have 30 options. They have at most 2 and in many places they have 1 option.
National ISPs like Spectrum/Time Warner Cable, AT&T, and Comcast/Xfinity have an oligopoly. They have divided up America into their own markets and purposely avoid entering each other's markets to avoid competing with each other. With no competition, they are free to charge as much as possible, avoid providing good support, and can provide suboptimal service (ie, low and asymmetric download/upload speeds, terrible latency). [1] The problem worsens if you live in suburban or rural areas. Of course there are exceptions where coverage overlaps due to sharing infra, but that is rare and possibly priced in.
It's worse than collusion. The break up of AT&T resulted in a legal construction of Franchise Agreements that legally granted regional monopolies in all major population centers in the country in a deliberate bid to avoid Sherman antitrust rules. It's not merely collusion, you literally cannot compete by law.