the whole united states are based on a low bid system. which is stupid to me. one of my teachers in college was from France and he said most of Europe works on the Avg. construction cost system. whoever is the closest to the avg of all bids gets the job. The low bid system has some huge problems and one of the bigger ones is change orders by low bidder, realizing an architect made a mistake and its gonna cost alot to fix, they wont say anything and day after contract is signed turn in a change order for a large amount of total project cost. In Europe most architects wont allow a change order unless owner request it. so if there is a question about construction it gets asked fixed and there are alot less project blown way over budget because of it.
One of my past clients was in private-sector construction, mainly commercial buildings. Their method was to automatically throw out the highest bid and the lowest bid, assuming either a mistake was made, corners were cut, something was overlooked or left out, etc. They figured it kept the estimators/quoters/sales reps at their subs on their toes, too. Knowing the rules of their game, it made them shoot for the most accurate bid they could, not low.
I did work for one state-funded agency at one time (IT subcontractor). Never again. It was time and materials, but I had to re-bid every 90 days to keep the contract. Kind of a "i charge $150 an hour, I anticipate x hours of server routine maintenance, 10 printer repairs, 18 virus or malware fixes, etc, etc, over the coming 90 days. Stuff you really can't predict. Then at the end of 90 days, it was "well, we see we had 11 printer repairs, not 10, why?" Stupid, because they had some discretion as to who they picked, not necessarily the low bid, but the lowest bid that would do the requirements of the job to their satisfaction. So basically, as long as they were happy with my work, they could keep me. But I had to do a proposal every 90 days, and they got 3 or 4 other tech guys to do the same, every 90 days, and I kept them for about 8 years (until they lost funding in 2008/9). Same 3 or 4 guys kept bidding every time though (at least on the record....I wondered more than once if the ED wasn't just changing the dates on their old proposals).