You got downvoted for the hyperbole, but there's a lot of truth to this, in my experience. I don't think this is limited to big shops, either. There is a psychological phenomenon where people tend to place more value on things that have cost them more; I've experienced this myself when I've purchased a new vehicle—all of a sudden, it's the best vehicle on the market (it must have been, since I made the decision to buy it). The same thing happens with large business contracts.

As an in-house employee, it is incredibly frustrating when a vendor is automatically more credible than me, even though I've spent years building knowledge of my own company's business and systems. But I have experienced this both at my current 20,000+ employee enterprise, and a previous company where there were 5 employees.