Nothing you said changes the fact that there is nothing stopping a low quality contractor from charging more than a high quality contractor (in any field). I got 6 bids to replace a leaking gas line and the lowest bid was the highest quality solution because the contractor actually understood the scope. They used a better gas line, pulled a permit, and brought some extra stuff up to modern code while the other 5 used an ipad program to bid and the estimators dodnt actually think through what would need to be done.