Uncommon and rare like random are concepts from the human perspective.Natural Laws and processes are indifferent. Chaos theory explains the variability of the outcomes of cause and effect events within the limited range of possible outcomes whether rare or common.I guess I'm using random in the wrong way. Might be better off saying uncommon or rare.
What is by the way random is the timing of individual cause and effect events. The timing of an individual decay event in the radioactive decay of a mineral, but the rate of decay of the radioactive mineral follows a consistent pattern and predicable over time. This is also true of mutations the timing of an individual mutation is not predictable, but the pattern and nature of mutations over time is predictable. The individual atoms and molecules involved in cause and effect events follow the Laws of Nature and processes.