Mobile operators build and run them because they make a profit doing so, and fishermen, carpenters and porters are willing to pay for the service because it increases their profits.

手机商建立及运作这个行业是因为它们能够赢利，而渔民，木匠和搬运工为手机付费是因为这项服务能提高他们的收益。

youdao

According to Burmese military sources, the army could not function properly without press-ganging villagers into service as guides and porters.

BBC: Burma "slave" probe opens