What a load of BS. Whoever said this was either high, is taking the p*ss or has a political agenda. No skilled farang will be willing to work in Thailand for less than 30,000 at the very least, which is twice what a Thai will be happy with, so it has nothing to do with "farangs" i.e. Westerners.
However, I have noticed a growing trend in employing Burmese workers for less than what a Thai would cost. This tendency to practice social dumping is nefarious IMO. Thai politicians should increase Thai salaries and social benefits, not encourage looking for cheaper alternatives in poorer countries.