Ah Seng, many of the Thai construction workers here are earning well above S$1,000 and some even above S$2,000. They value-add beyond digging grounds and laying bricks. They can assist in simple engineering calculations and become foremen.They go get Singapore driving license for cars and trucks. They don't demand a higher pay, they simply command a higher pay, according to market.
Go to Golden Mile and see the Thai workers at rest and leisure. They can afford Singapore prices for food, beer, cigarette and taxi. In fact, Thai food in Singapore usually costs not only more than Thai food in Thailand, but costs more than Singapore food in Singapore.