Why don't all these distro maintainers add their own back doors, and mine crypto off our machines without our knowledge? Surely, there is some legal fine print

Why don't all these distro maintainers add their own back doors, and mine crypto off our machines without our knowledge? Surely, there is some legal fine print they can add that would let them do that. There is very little incentive for them to maintain these systems, given how thankless and underpaid the work is.