Things are similar in California. My boss will show me the bid amounts and he is smack in the middle nearly everytime. And wouldn't you know it, but the GCs are no longer tossing the lowest but tend to go with it these days. I wish I could watch tapes of these jobs afterwards and see how these other contractors managed to finish the job for such a low bid.
I think you will find a few things.
1. These guys know exactly what they bid down to the last wire nut.
2. These guys are doing things they have done many times before and know how to get it done with the bare minimum.
3. Many contractors do a very poor job of cost control on material purchases. If you are paying 10% more than the next guy for materials, you are going to get hosed on every job. And do not believe the lies from the supply house about how you are getting the best deals.
You can switch brands of wire nuts and get a perfectly acceptable wire nut for half or less than what you might be paying for a wire nut now.
It is possible to get deals on things like conduit and strut on a project by project basis. And the value of the projects does not have to be as high as you think. These days as little as five grand worth of strut can get you a heck of a deal if you just ask for it. You have to ask the right questions though. Certain items are often available at very good prices while similar items are not. For instance, it might be that slotted strut is 20% cheaper that solid strut (hint - this particular example is based on recent experience). Sometimes the zinc plated strut fittings are more than the painted ones and sometimes it is the other way around.
On a few occasions, I have found that McMaster Carr is willing to sell me parts cheaper than the supply house. Guess who gets the order?
Sometimes the big box store has better prices on some things. Guess where that material should be sourced from?
4. These guys will ding you for every extra wire nut they use.