On public hard bids, the award normally goes to the lowest bidder that is both responsive and responsible. Low price alone is not enough.
On private work, the owner or GC can choose anyone. A sub with the low number may still lose to a sub with a complete scope.
Low is only good if the price is right. A sub that is low by a wide gap should check its takeoff for a missed item.
Ask the GC how your number compared after the bid. That feedback helps you price the next job.