Yes, you are crazy. It is insulting to have some A-hole walk into your shop with a brand new part they bought elsewhere and ask you to fit it. Most shops will but will charge you more for the service than they would've had you bought it there. The shop I worked at in BC would fit any part for free if you bought it from us, we'd charge like hell if it was from the Internet and politely let the customer know that we fit stuff for free. If you expect to waste someone's time by asking for info and then shopping elsewhere, you should also be expecting to be treated badly.
What a great way to run a business and a great reason why people who ride bikes shouldn't necessarily own shops
A-hole walks into a shop with a front and rear derailleur he bought at CRC
A-hole bike shop: Fuck off mate (politely of course!) we only fit what we sell
Profit = $0
Progressive bike shop: Rings customer
mate, your cables and housing are cactus and will need to be replaced
Also notice that your chain is beyond 3/4 worn, so when you order again you will need to get a new cassette and chain or we can supply and fit brand X for $xx
Customer: Mate just go ahead and fit the cassette and chain and change the cables
Profit: Well, a business never went broke making a profit