Soil contamination is an important aspect why brownfield are turned into golf courses.
I don't know how it works in the US but in Quebec, soils are classified like to
NC - no contamination
A - light contamination
A-B
B
B+
B-C
C
C+
DD - dangerous soil
So, a brownfield site often contains soils classified as B+, B-C or more contaminated. Depending on the contamination, your potential of development is limited.
For example, you can't built houses on soil with a contamination worse than A-B, since kids would have access to the soil and emanation can be a problem. If you want to built a house on a C soil site, you would have to treat the soil or truck it out and domp it in a specific place (expansive)
On a golf course the tolerance is higher, I think B-C is acceptable because of the use, no little kids technically etc. So no decontamination is neccesary
Depending on the soil structure and stability, you could go higher (C or C+) if you agree to cap the site with a foot of clay.
Just to give you an idea of the cost, on a construction site (not golf) they were digging up some contaminated soil and the engineer comes to me and said... This is some DD soil, that's 300 $ each excavator scoop...
Once you caracterized a site, (contamination is not equal everywhere) you'll use the least contaminated areas for houses and the worst one for golf.