Why these laws and not others?

These laws are what the winning repair rule leaves standing, and the rule won a competition held inside the world. Repair is how neighboring observers settle a disagreement. A candidate rule scores for stability, settling the same way whatever order the repairs run in, and for producing observers, regions that keep stable records about what comes next. It loses points for every symbol it takes to write down. A rule that repairs nothing is stable and cheap, and produces no observers. A rule that copies everything pays for the copies. Moving two disagreeing readings to their midpoint is where the pulls balance. Rules share one finite capacity, and the average score climbs at a rate equal to the spread of the scores. No shelf of other universes is needed, because the competition ran over rules.