How can estimates have so much range?

Construction is no different than any other industry. All people/things are more/less expensive than others. That can always mean a few things. Quality often play a role. Same with efficiency. Also what is included in the estimate makes a big difference. Think of buying a car, take a Honda Accord for example. The price of the car can range from $26k to $38k, for the same car. It’s all what’s included in that car that makes the price differential. You want to always make sure you are taking those extras into account when assessing pricing.