To the original post - The Costco program is nothing special in the auto industry - Costco wants it to be, but its not. Its just a lead generation source for dealerships. That's all. The "Costco Price" is set up by the dealerships that participate in the program. The dealership can, and most of the time will, sell you the car for less if you push.
To the ensuing conversation - I actually work at a dealership that does not negotiate. At all. We have one price for each model and if that works, great. Its a super easy and transparent process. But you need to understand the amount of work that goes into generating that price. Its not a blind shot in the dark price that we make up. We constantly secret shop the competing Subaru dealers in the area, consider truecar, supply, demand, etc and we update it (if needed) once a month. A perfect example is the 2018 XT Forester. It was priced a couple hundred dollars over invoice until Subaru announced that they were discontinuing it. Price shot up $600 the next day.
95% of people absolutely love it. Its our best price right up front. No games, no haggle, no hassle. No hidden fees or added accessories. Its super easy on the customer and myself as a salesman can focus more on customer service rather than how much profit I'm going to generate for the dealership and myself.
There is still that 5% that won't believe me no matter what I say. And that is fine, they are welcome continue shopping. Perhaps they will save a couple hundred dollars, but more often than not the competing dealership will get them with their hidden fees and such
My point to all of this is simple. If Subaru came out and said "No more negotiating." All dealerships have to sell their cars at MSRP/Invoice it would be the best thing for Subaru. Customers could focus more on what they like about the car and dealerships would be able focus more on taking care of the customer rather than how to squeeze ever penny of profit from customers.