I do believe you.... and understand where you're coming from, but you're using the same jargon and reasoning for what these salespeople use on everything today and not logic.
The main reason most shops will charge less for magnetics is simple. They don't have a place to do a truck indoors in wintertime or bad weather. Therefore, in order to be competitive, they hafta take that advantage away from you and make their magnetics cost much less. This is what decreased the value of magnetics. Using fancy words and made up rationale is their way of getting business. It goes without saying for the other things that take place in a shop.
If one works outta their house or a small rental building with no bay space....there are things they cannot offer in a commercial world, so they tend to bring novelty things in, trinkets, business cards and other things which a regular sign shop actually doesn't do. When they were able to start producing things with small digital printers in their dining room, they had to use the bedroom for the laminator, but here's hoping little junior won't get sick from the smells. Out comes latex, which is better, but still not good for in-home usage. Same goes for the person who doesn't have room to build a sign in-house. They probably don't have the tools, supplies or know-how to do it, so they look for lesser grade substrates/materials, thus lowering the value of a one time..... good product. Over time, the end-user starts seeing this kinda products and the bigger shops will lower their prices to now compete with the bottom-feeders.
Can we do it ?? In our shop, we can certainly compete with these guys and if we wanted to, could blow thier doors off, but why ?? They are the ones who have the cheap-a$$ customers who waste time and don't wanna pay for anything in the first place. Those shops get known for doing that kinda work and they remain in that rut for a very long time..... if not forever. Us, we're working smarter and using our tools to their fullest and getting paid what we should. There's been occasions where we wanted to smack a competitor right between the eyes and believe me, they can't produce the stuff and make money for what we could, but again..... why ?? Just to keep them out of our hair from time to time.
I understand your thinking, I just don't fall prey to it. We generally get $350 for a pair of doors with a digital print or very simple 1 or 2 die-cut vinyl on them. Most vans are at least double that and higher. We do an average of 4 to 5 trucks a week.