Commercial airlines are generally used for long distance trips so they'll naturally rack up more miles between deaths. You'd see the same thing if you compared

Commercial airlines are generally used for long distance trips so they'll naturally rack up more miles between deaths. You'd see the same thing if you compared freight haulers like Swift, Schneider and Walmart to companies that do a lot of local delivery. Commercial airlines are also flown by a professional crew instead of the public making the utility of the comparison limited at best.