Fair point but as I mentioned in my opening post the lines are being blurred. If a screen printer and a commercial photo lab can do it, what's to stop you?
This is all based on the concept that digital printing IS the sign industry... which it absolutely isn't.
If you can print onto vinyl, banner stock or PVC this means you can print... it doesn't mean you are a sign shop.
Unless you know how to take the raw printed media and apply it to a vehicle, hang it safely from a building or transform it into a fabricated sign structure then you are still just a printer.
If all you do is print then screen printers and photo labs are your competition... if digital isn't the only trick in your book then you are still the sign shop and they are still just the printing people.