Why isn't lamb more popular in the US?

Grilled lamb chops, mmm!
And one of the best meals I ever had was a buffet at a Glasgow hotel. A highlight was a tender rack of lamb.

A couple of John Buchan’s books, set in Scotland 100+ years ago, mention “mutton ham” as a special treat. I suppose that means a leg or shoulder of salted smoked mutton?

If anyone hasn’t read Roald Dahl’s “Lamb to the Slaughter” yet, or seen the TV version, here it is:

The wikipedia article contains spoilers: