In most parts of the USA winning on a public project requires three bids. Why do the same companies always seem to win? In my neck of the woods (The Bay Area)

In most parts of the USA winning on a public project requires three bids. Why do the same companies always seem to win? In my neck of the woods (The Bay Area), one company seems to get all the jobs. The company's name rhymes with Gelato. I started to look carefully at the bids. (I got a General Contractor's license a while ago, and it an easy test, and verification of work experience is a joke.) Ok, I looked into the owner of the contractor's license, and in all three bids, they had a "Gelato" as owner of the company. It looks like the "Gelato" family sent three kids to Sacramento to take the test, and get their licenses. They all bid on the same project, and one wins. They must share the million dollar equipment, and pool of employees though? Is it legal? I don't know. Do I know for a fact this is how it works--no. (There's a bill, I believe up for vote soon, in Sacramento. It requires all bidding parties to verify their company us big enough to do the project. I don't think we need a bill like this. I don't think small companies bidding on huge project to is a problem. If I am right about "Gelato" construction company--authorities should look into the bidding process. There us a reason, besides inflation, that public projects get more expensive each year, and never seem to end.)