That would have to be calculated as an opportunity cost, That can be fudged to anything. Many real estate development are only successful because the property was bought from the original bankrupt developer.

Opportunity costs can also be a negative number.

The article is about a single family home. And pretty much all the costs mentioned in another comment (and maybe more) apply to a manufactured home as well.

That shows up in the “land” field.

What is SFH?