MIT and source out on GitHub is the easiest way to build trust. You will find that some people simply "steal" your work in this arrangement, but much like with movie piracy I don't think they ever intended to compensate you or anyone else.
So, we wind up alienating all potential customers because we are so worried about preventing ideological crime.
People will steal your ideas and they will get away with it. The more you react to this in first order terms, the more it will destroy you.
Most money in software is made with support contracts, not the initial sale.