What do you mean zero cost? United charges my parents and enrolled friend $36.50 for every domestic leg. Over $60 for International legs. If you have a 2nd enrolled friend the charges are even higher. If they can't fly direct and have to take 2 or 3 flights to get somewhere the charges add up fast enough that it's usually worth it to just buy a ticket on Spirit or Frontier.

I would absolutely prefer United to go to a once a year fee then unlimited free travel like Delta does. My family easily pays over $500/year for United benefits and they don't even fly that often and never international. If they were frequent fliers the cost would be huge.