Freakonomics discusses if insurance companies should pay you not to get full treatment for what ails you, but get hospice instead.
One problem not mentioned: Good hospice care is just as expensive in many cases, since full treatment often lets you strong enough to recover, work and care for yourself... (and insurance companies don't count in the lost wages etc for family members who care for the dying patient in their homes). But I do agree that good hospice can let you live just as long in some cases, and that doing "everything" is sometimes absurd.
But it's not age as much as "comorbidity": If you have five or six things wrong with you, maybe chemo isn't the way to go. But if you are in good health otherwise, well, why not?
But when hospice only covers six months treatment, what happens when it disappears, and you are still alive? This is one reason that people often don't sign up until terminal.
the other problem is that a lot of the ICU etc type of care is done not on "hopeless cases", but in cases when there is a chance for recovery with a good quality of life.
Finally, minorities know that they could be offered less aggressive therapy due to racism. Which is why they hesitate to sign DNR orders etc. No, they are not paranoid: I've seen this.