I only have those shows to go off so I’m no expert lol but I can try to give you a scenario.
You go to purchase an iPhone, pay cash and take the phone home. A few weeks later you’re accused of stealing it and the seller has proof that it belongs to him.
In small claims court it is your word against his that you paid for it and the seller is claiming that the hand written receipt is fake and not his handwriting. If you can show your bank transfer it shows credible evidence that can’t be disputed.
Someone feel free to correct me if I’m wrong as I know these shows are mainly done for entertainment rather than a serious law program. Although they do claim that they are genuine and rulings are final etc