Elevator Bellcrank Ribs

I'm working on the forward most bulkhead in the aft fuselage that supports the elevator bellcrank ribs. It's going well but I had to ask Paula, "why is it that the parts that won't be seen, like the elevator bellcrank ribs that I'm working on, come out perfect and the ones that are exposed are perfectly fine structurally but get the small blemishes?" These ribs will be behind the cargo compartment wall and will only be seen during building and the one a year maintenance checks.