Volume builders operate a 'low cost' business model which means cheaper contractors, building materials, and administration, and building supervision QA costs etc. which enables them to provide a more affordable build. You get what you pay for.
Norfolk you are correct, "If given permission" but if you read the following statement form Alexp from his informed opinion "Will you be able to provide full list your existing customers and provide new potential customer an ability to interview ALL of them or at least some of them randomly?" I cant see it being random if the builder is providing the information to the customer, most builders would supply such contacts yes, but do you think they would hand over names and numbers of unhappy customers? probably not. I did work for a project home builder for quite sometime, and product reviews actually worked both ways, most 5 start reviews would not be genuine clients of that builder, on the other foot, most 1 star reviews of builders are not so genuine either. I remember one such review of the company I worked at, a genuine person got on and said that we had not installed any termite treatment to the house, we ignored there calls and never fixed the problem, Stay away, they are bad etc etc. When reaching out to him for his address, number etc we received no reply. The company I worked for used granitgard and a photo needed to be taken on every job by both the termite company and the bricklayer prior to proceeding
They didn't send the photos they didn't get paid, so every builder is good and bad, every builder has good and bad products, every builder had good and bad trades, mistakes happen, the really good builders, put up their hands and talk to the customers when the mistakes happen, these are the builders I look for to work with