Imagine you arrange some "send goods, receive payment later" kind of deal with someone; you send them the goods but they never pay you. So you bring them to cou

Imagine you arrange some "send goods, receive payment later" kind of deal with someone; you send them the goods but they never pay you. So you bring them to court... and now you have to prove that they did not pay you. While they claim they did and even gave you a signed receipt which you must have thrown away. So naturally, because in most civil cases its the other party's inaction that's supposed to be punished, courts adopt "guilty until proven otherwise" stance. Now it's the other party that has to show a receipt signed by you, or to show their bank statement that says they've transfered money to you, etc. That's one reason why there is so much paper trail in business and commerce — so that's when someone sues you, you could use all that paper to cover your ass.