(non US perspective here) Another element is that a lot of the expense is closing the road, site management, safety setups, materials, having the plant (machinery) on site etc.
Despite being visible, having relatively cheap workers hang around when their role is not needed 100% of the time doesn't add much to the overall cost.
And you can't effectively redeploy them elsewhere to other jobs during those gaps anyway.
Despite being visible, having relatively cheap workers hang around when their role is not needed 100% of the time doesn't add much to the overall cost.
And you can't effectively redeploy them elsewhere to other jobs during those gaps anyway.