These guys get duped into thinking they'll get a good paying job but once they cross the border they get their passports taken and then they become used like slaves and get physically punished if they don't meet certain quotas.
Sadly, the Cambodian (as well as the Burmese) government don't actively try to raid and disband these operations. These operations probably have connections with the current government or police that allows these operations to carry on and flourish....