Commuter today means someone who commutes usually toward downtown from less-downtown, regularly, for economic reasons, usually employment. That is a slight change from its original meaning, which referred to someone who went back and forth (that part’s the same), and so bought a pass—multiple tickets for a reduced price. The commuting referred to a reduction in the per-ride price from buying multiple tickets up front—the combined payment was the “mut” part….
This may not make any sense. Commune with the bumblebee and it may become clear.