Buying from an international seller?

[IsDVCForMe?]

It’s been so many years I don’t remember.

It’s an issue for the buyer because the tax code says so. https://www.irs.gov/individuals/international-taxpayers/firpta-withholding
It is the buyer’s responsibility to pay the tax to the IRS. It’s sort of like when your employer w/holds your income tax from your paycheck & sends that money to the IRS - the IRS makes you the buyer responsible for w/holding the real property tax owed from what you pay the seller & sending that money to the IRS.
There have been cases where the tax was not paid or not correctly calculated/paid & the IRS demanded that money from the buyer.
I’ve always assumed it was set up that way because it’s far easier for the IRS to get the money from a U.S. taxpayer v. a foreign non U.S. taxpayer .

Yep, makes sense it’s set up that way.