https://www.law.cornell.edu/wex/adhesion_contract_%28contrac...
They are generally valid but courts may limit what may be enforced to a standard of reasonableness.
See the Wikipedia entry on Clickwrap, and Planet Money episode “Surprise, you just signed a contract!”
I believe that any contract that doesn't contain "unconscionable" or illegal terms, is agreed to by all parties, and that involves consideration, is valid. I don't think that the ability to negotiate the terms is a factor. It's hard to see why it would be -- if I get a "take it or leave it" contract that I can't accept, then I can always just not enter into it.
The Courts have, in my opinion, abdicated their responsibility in ensuring that a contract is considered invalid by recognizing take-it-or-leave-it clickthrough licenses as valid.
Not doing so, and requiring a negotiation pipeline, would rein in these types of encroachments, because the burden incurred by playing these types of games would provide a better feedback loop to companies on what is vs. is not conscionable.
This much is true and I think it's a well-established fact that consumers don't read the terms and conditions that they "agree to" by clicking a checkbox, because it's dense legal boilerplate and it would take hours to read and understand. Nobody is going to do that to sign up for a streaming service. Any terms not directly related to the streaming service should be unenforcable on that basis alone.