Rules vary but in general, unpaid tax liens are sold to investors on a silent auction basis and if the same investor pays the tax lien on the same property two years in a row, the investor is allowed to foreclose.
If you read the article, I think you will agree, this business in DC is unscrupulous at best and criminal at worst. a house being sold by the government to a lien company for $287 to pay the tax bill and then being sold by the lien company for $129,000 2 months later. There’s criminal activity occurring there.