I would ask those same questions about cousins. The funeral one seems irrelevant/circumstantial, but the others imply a person who is willing and able to make personal sacrifices for another person. I'm fortunate to have many of friends who meet those criteria, and maybe one cousin that does.
I'd also say that though friendships tend to be very homogenous by age when we're young, that can change considerably as we get older. But because longevity is one of the key factors in any relationship, most of my closest friends are +/- 3 years of me. And in support of your point, it's often when we're young and mostly have young friends that we need support, and those friends are not likely to be in a great position to help.
EDIT: I actually did get help from friends' parents as a kid! As well as an adult "family friend". Those types of connections shouldn't be overlooked.
I'd also say that though friendships tend to be very homogenous by age when we're young, that can change considerably as we get older. But because longevity is one of the key factors in any relationship, most of my closest friends are +/- 3 years of me. And in support of your point, it's often when we're young and mostly have young friends that we need support, and those friends are not likely to be in a great position to help.
EDIT: I actually did get help from friends' parents as a kid! As well as an adult "family friend". Those types of connections shouldn't be overlooked.