This is because of a wrinkle in Oregon and I believe Washington law (and probably in any number of other states too), which provides that if an unoccupied home is advertised for sale and you agree to pay the seller an amount of money or credit within the price range and they accept the offer, you have the right to move in.
Typically it is a bogus offer made in the form of an IOU sent to the office of the seller as a piece of return-receipt requested mail.
By the owner signing the receipt, the "buyer" claims in court that the offer was accepted, they post 'no trespassing' signs and have any representative of the seller arrsted if they try to reclaim the property, and it can take months to prove that the IOU was worthless and not real consideration for the property.
Certain lawyers specialize in keeping these claims going for over a year in exchange for a nominal fee.
However, there will be civil lawsuits and sometimes criminal prosecution for fraud, unlike the UK.
What has the world come to?