When I was shopping for a TT, the salesman saw my wife's van and asked what my tow vehicle was. He said the van would not pull a TT. I told him about my F-150.
Also at an RV show I asked two different salesmen what I needed to do to my F-150 to pull their fifth wheel. Both told me to buy an F-250.
The guys with a well established dealerships simply do not need the hassle, there are enough issues with the normal day to day activities.
The bigger problem is the dealers only know the towing ratings from the manufacturer, they have no idea what the customer considers essential.
My F-150 has a tow rating of 9500 lbs. I can tow it if I want to leave my wife and dog home.:)