Some default is expected in this model, and the pricing reflects that. A seller-financed land deal is a purchase where you, the seller, hold the installment contract instead of a bank. The buyer pays you monthly, and your protection comes from the paperwork rather than from a credit report.
The down payment is doing a lot of the screening, though it isn't the only tool. Many operators do pull a credit report or verify income, mostly to set the down payment and rate rather than to reject anyone. A buyer who puts $2,000 down on a $20,000 parcel behaves differently than one who put $500 down.
What gets you the land back depends on the instrument and the state. If you sold on a contract for deed, meaning title stays in your name until the last payment, some states let you cancel the contract after notice, and others treat it like a mortgage and require a full foreclosure through the courts. That difference is worth confirming with a local real estate attorney before you write your first contract, not after a buyer stops paying.
The part people underestimate is that the property taxes and any liability stay yours while you're waiting. A stalled buyer who quits paying taxes too can cost you a year of holding, plus the cost of remarketing the parcel. Build that into your numbers rather than assuming a clean resale.