This is one of those things that just really weirds me out about America. Old people in McDonalds.
In England, you never see anyone over, say, 35 in a burger joint unless they have kids or grandkids with them, but over here they have, not to put too fine a point on it, old people in McDonalds.
In the USA, the burger joint has been part of the culture since the fifties, so many people who grew up with this have now become, in a manner of speaking, old people in McDonalds.
It's no more unusual than, say, going into a chip shop in England and meeting old people there, but still, y'know, it weirds me out.
Culture shock: it's not just for bumpkins in cities any more.