"cost would be minimal in the scheme of things"  If you sell your car and you only get 2 per cent more than it is worth;  (Worth $1,000 and you get $1,020)  and you have to pay  2.5% tax on the sale that means you have to pay $1,025.  So you now have to pay more than your profit was.  Multiply that so the $1,000 is really $1 million dollars of a small construction project, and you might understand the effect of this tax.  ($20,000 profit; $25,000 tax.  Knife River will have to pay $5,000 more than you actually made.)