Company representatives have been known to not show up. Other times, couriers might outnumber available seats, even with advance confirmation. Courier companies don't offer refunds. If travelers show up late, they lose their tickets and security deposits. But the loss to courier companies when travelers don't show up is even greater, because they have to pay extra to send employees.
Luggage remains limited too.
The courier's personal luggage becomes whatever they can get into one, and sometimes two, carry-on bags. Anything more and you board dressed like Bib the Michelin Man. Mike Fleming, a spokesman for the U.S. Customs Service, adds that contraband is not a problem. I'm not aware of any instances of seizures involving individuals flying as couriers for a legitimate shipping company. If someone hands you a stuffed poodle and three boxes of dried figs as the airport, however, take care.