I am not a lawyer. Suppose a rental car matter ended up court. I would rather not have to say to the judge, "I spent 10 minutes thoughtfully reading and evaluating the contract, and after careful consideration decided to accept the agreement." I would rather be able to say, "Gee, it was printed in gray ink in tiny type on the back of the paper, and they told me to just sign here on the front to get the car. I needed the car, so I did what they told me."
I never accept the "standard contract" when it comes to employment or consulting gigs - then I always read carefully, propose alterations, and often talk to my lawyer. But if it really is a "standard contract" signed by millions (including, presumably, lots of lawyers, too) then I am inclined to balance the risks and benefits and opt for ignorance over informed consent.