Probably, but from personal experience true.
Tim, you are being judgmental about a situation that you don't even know all of the details. There are a ton of situations where the change has valid reason and only couple where the contractor is a scumbag who is irreputable. You could be considered just as irruputable if you provided metal boxes and charged the extra markup when the customer was looking for value, and more often than not, an Engineer uses boilerplate specs that they failed to completely modify for any one specific project. So maybe they are the irreputable ones who didn't provide the customer their full service. The thing is you just bandy that around like you are "holier than thou!"
Years ago a training program defined quality as "conformance to requirements" It was concept that took getting used to. But if a person goes to a car dealer and asks for a Pinto, but the salesman delivers a Cadillac, that is NOT a quality product. Especially when the customer is handed a Cadillac bill. Plastic boxes with Romex is a standard installation and there is nothing wrong with the quality of it. You posit that you can crush a plastic box with you hand. I will take your word for it, but on the other hand, drop a plastic box form a ladder and a metal box from a ladder, and the metal boxes are going to be damaged more often, so maybe it is the metal box that is inferior? I prefer higher end electrical installations as well, and am stuck up enough that I avoid romex jobs, but that doesn't make them inferior.