All of my locks are polished internally,springs,screws,tumbler,the internal surface of the plate, The flintlocks are sometimes polished,frequently not. Caplocks,both sides polished with more attention paid to the inside than the outside.
You're partly right about most makers not willing to pay for the work in such a lock but I only work with the few who will. I offered to make 10 Twigg locks at $300 apiece and 9 people bought all of them, I have only #9 and 10 to go plus one for a customer in South Africa who was out of his country when I made the offer. He wants set triggers with that one also.
Years ago,when I offered polished and detailed locks,they were next to impossible to sell and I'd get phone calls telling me how cheap they could get a lock for from wherever they bought from. My answer was and is."Go for it"!
I replied to an ad from Guenter Stifter in Germany about his cut flints and he sent me some samples.I then sent him a sample of what was NOT wanted in the USA for a lock and he said they would buy any and all I wanted to make and not to worry about $2. Pistols were the big thing then in Germany and I supplied a flintlock of the Bailes style and a percussion lock like one found on a Swiss Weber&Reusch
31 caliber target pistol. After that,there were Schuetzen rifle locks and the curved double set triggers for the fish belly stocks used on them.
I am semi retired now and if I make a lock for someone,that's fine and if not,I am not concerned. I still get requests from a German shop for different locks and I make up mostly Shuetzen locks and once in a while,a Durs Egg using the L&R external parts with my own custom mechanism inside.
Now it's a fun and games thing,nothing serious.
Bob Roller