It is somewhat frequent for the buyer to be local, and the money to come from overseas. Son buys a house with his dad's dubious-origin money.
And given the lack of required information & intentional ignorance ("so, Mr. Boriskypov, would you describe yourself as an oligarch?") I'm not sure how that dataset could reliably identify "international" purchasers.
The dataset was from a real estate company's reports from individual realtors. I'm confident the realtors know the origin of money.
I think a more appropriate criticism would be to focus on the narrow class of purchases (cash only) or small sample size (n=300, though the company represents 10% of the real estate market in the SF Bay Area). Unfortunately, it's the only published information I could find.
