It’s actually not that surprising that it’s tougher to get into an Honors program at a good school than it is to become a NMF.
There’s some esteem for a school to note that they have “x” National Merit Finalists enrolled, but the reality is that it really only takes one good test for a student anywhere in the country to become a NMF, and that’s the PSAT they take during their Junior Year. The confirming SAT score is rather pedestrian and wouldn’t be enough to get a kid into many of the top schools. Honors programs likely don’t even consider NMF status, they look at the whole package (GPA, SAT/ACT, and EC’s).
NMF is incredible for kids that want to go to the schools that offer NMF $$, but in an of itself it’s not really an overly impressive achievement.