Do new bumpers come in primed ? what does "primed" mean ? thanks
Yes. The urethane skins come with black primer. It's an undercoat that prepares the surface for the color coat. If the primer was not there, the final paint would flake off. By the way, the primer needs to be properly sanded ("keyed") and cleaned with solvent before painting, or the paint will flake off anyway. If you see cars with the paint peeling off the bumpers and with black underneath, that happened because somebody didn't key and clean the primer beforehand.
Don't say anything; they know. What you need to worry about are the fly-by-night el-cheapo bodyshops. They're the ones that will skip steps to pump more cars through.