The problem is Gulfstream is an airline, not just a flight school, and YOU ARE PAYING them to fly as an FO on revenue flights, i.e. your are paying a company to work for them. Not to mention your filling a seat that should be filled by pilot who is being payed industry standard wage to fly that aircraft. The flight schools you metioned aren't using students instead of hired pilots to run a scheduled 121 service. Think what would happen to this profession if all airlines were to do this. That's why people hate Gulfstream.