I know this doesn’t help much. But ALWAYS ALWAYS do a walkthrough in the way to closing to make sure everything is gone. If they need a couple days you delay closing, if they need longer you have the title company/lawyers withhold a LARGE amount from the sale that seller doesn’t get until the property is vacant and repaired. ($10-$20k minimum.). After all, they’ll get that money in 5-10 days when they move out. It’s pretty easy to see if someone is going to be out of a decent sized house in the next 7 days.
If you google home seller won’t move out you’ll find sellers that have stayed for more than a year.