Customers drive this policy. Make no mistake about that. If it was worth the money dealerships would work on old bikes, but today it's not worth it. Like others have stated, the old rat's nest shows up and they want a show bike returned to them for minimal dollars.
One of my favorite memories of doing tuning was a customer's question, "How much do you charge?" I told him my hourly rate - what ever it was at the time. I told him to expect about 2 - 3 hours of labor. His reply, was representative of many public motorcycle consumers, "I only have $250. You're going to have to work faster."
After 3 heart surgeries last year I no longer tune for the public. It's not worth the effort, stress, or dollars.
I had a customer from many miles away call me recently to tune another crazy hot rod build. Think 30% bigger engine, cams, headwork, huge throttle bodies. Should have been an interesting time. And could have been, but it could also be a nightmare that has lots of high $$$ parts thrown at it and still has a wiring rats nest keeping it from starting. (I've had those bikes dropped off for a Power Commander tune - customers still expect basic tuning price when you have to spend 4 hours sort their poorly performed set up out in order for the bike to even start.) I told my super hot rodded bike customer that I'm not tuning anymore. He was upset and told me a regular dealer won't touch it.
I tried to explain how it's not worth working on. I no longer have garage keeper's insurance. Forget breaking his bike or blowing it up, - if a tree falls on my shop, we've established a bailment where I am now responsible for the bike since it's in my care. This is risky for all vehicles, especially running hot rods that have never seen redline before - under load. I told him how a local shop built a supercharged bike and wanted me to tune it. I refused. They were upset. I told them I'm closed, no insurance. They said, oh, the customer will pay your insurance. I told them I need $800 just to open up. Heads exploded. They figured $50. "It shouldn't cost that much per bike!!!" No. But the Insurance company doesn't charge that way. They want a bunch of cash up front to restart insuring me to work on your shite. I have no interest in paying out of my own pocket to tune your bike - surprising as that may sound.
I sent Mr. hot rod to a shop that specializes in supercharged hot rod bikes. Guess what? They were not interested in tuning a naturally aspirated monster they didn't build. He called me back begging. What can I do? I'm not paying out of my own pocket for insurance and I'm not taking the risk. Sorry.
A week later the shop down the street calls begging me to tune a customer's bike because the same local tuner I referred them to refused their supercharged monster. LOL
The lesson here is, there are a lot of customers out there, but owners of old rat bikes don't pay top dollar (usually) for the extra work their bike requires. Even owners of expensive super hot rods don't like paying top dollar for work on their bike after blowing all their cash on their upgrades. Shops are interested in making money, not doing charity work. So the guys with 10 year old bikes are being categorized in with the rest of the old rat bike guys. Yes, some 10 year old bikes are still in perfect shape, but most are not. Dealers are letting the independent shops and speed shops handle that work.