Interesting. I wonder if this distinction applies within software as well. For example, systems programmers getting paid less than application programmers because the latter makes software "closer" to the user, and backend programmers getting paid less than frontend programmers for the same reason.
Yes, backend engineers do get paid more in general. I was just wondering why this runs contrary to OP's explanation that "closeness" to user triumphs job difficulty (when it comes to leverage/salaries).