Paper trails

Seriously, I have a room mate who complains that the record keeping isn't accurate and keeps insisting on doing business in cash. He keeps refusing to write cheques. I think there's something incredibly odd there. Why avoid an external transaction record if your going to accuse someone of lieing to you about how much you've paid? Wouldn't you to have something to be able to back up your story if you were doing this? This has to end.