In Arlington and the Washington DC metro area it is common that sellers leave the refrigerator and washer/dryer, but it best to check to see what the listing and what is in the contract dealing with which items will be left behind. It is also a negotiating point if you want them to stay and the seller wants to take them. Also, depending on the age of the appliances, if the seller takes them, you get new appliances that are your choice.
In my area, it is at the discretion of the seller.
Certainly, a built-in refrigerator (like a Sub-Zero) for example, would remain.........but otherwise, the seller can make that decision when the home is listed and disclose his or her intentions on the listing form.