I mean it's 2021. When I was growing up Kraft singles were common. Today I can go to a supermarket and pick up a block of Gouda.
Also, I think there's degrees of lactose intolerance? I don't really take full cream milk as is anymore because of that but cream and cheese and lattes are fine...
An aged, hard cheese will have much lower levels of lactose than a fresh, soft cheese, to the point where it virtually disappears.
And don't discount the mental factor. I've eaten balut (the Vietnamese variety that is older and more developed), dog, live shrimp, fish gut soup, etc. Other than balut, which has a livery flavor (not to my personal taste, though it's more pronounced with duck than with chicken), the flavor and texture were never particularly foreign or distasteful, per se; the aversion was mostly mental and simply an artifact of cultural familiarity. The dog stew I ate was delicious, but near the bottom of the bowl, my appetite sated, disgust reared its head and I had trouble keeping it down. Later that day I learned my partner had the exact same experience. Fermenting and consuming the lactation secretions of herd animals is, on its face, kind of gross if it's not what you grew up with.
An Asian friend once told me that when she came to America as a child and someone gave her cheese, she thought they were trying to poison her. I get the sense that that's not too far off from the common sentiment for those uninitiated.