I don't think it is commissions. The tour company owns the bus from the airport, the hotel they stay in, the restaurant they eat at, the massage shop they have massages at, the souvenir shop for purchases. The customers do not have a choice of where to go. I heard in the past some were kicked off the tour for wanting to be independent. Sure they employ some locals but there is no benefit for local businesses. Is pretty easy to leave the country with money or get somebody to send it for you.