Should be spelled out in the contract. I USUALLY see painters as part of thier prep along with caulking,plugging holes etc.I remember going down this path over caulking, but let's try it again with sanding...
Who is responsible for sanding new woodwork, painters or carpenters?
They always say it's thier job to make the carpenters look good.
I would think a quick sand on the installers part wouldn't hurt but back to the wording in the contract as far as responsibility.