Why do most anarchistic transactions (under the table cash) involve no receipts, paper trails or contracts? I'm taking sums of less than 100$

cross-posted from: https://lemmy.perthchat.org/post/264686

Once did a job, was supposed to get paid 20$, but was paid 10$, when we were discussing the difference in expectations didn't have proof and they thought they said 20$. Since then I always write and get a signature in case of problems