I don't know how the experience is in US, but in EU it's because GDPR is a complete failure of a law which doesn't actually solve any problem.
The GDPR is on the whole a very successful law which has improved the way companies handle personal data a great deal. What you are objecting to is specifically the part of that law which mandates consent for gathering personal data, and which resulted in these cookie banners. That's annoying (mostly because a lot of media companies rather continue hovering up data instead of critically assessing the need to do so),…
What is unfortunate that law puts the onus on implementing the dialog for individual sites, it should be feature of browsers. This way users could enforce from browser settings that they don't want to be tracked.