Even with the hint, I'm lost, I can't see any "feature" shared by LABOR and, say, 1a and 5a, much less every grid entry. How does the lack of a "U" matter?
Indeed, many sophisticated clues in service of a trivial theme. But, I got to write an Excel macro to skim the clues and pick out the relevant letters, so that was fun.
Is it so trivial? I thought burying the second message and reference in such well constructed clues and creating the highlighting was a work of art. I understand buddy’s frustration at not seeing it, but I don’t think the puzzle deserves to be rubbished for that