Waiters, chasiers, etc. of the western background are not eager to collect money from customers. It is as if they rely on something automatic, from Government's pension or medicare or foodstamp to the fixed paycheck from the boss.
So, the tips system I believe is invented to keep these waiting services enthusiastic. People in Malaysia work hard and cherish their earning while the westerners work like those you see paid by the government, and not only hoping for some undeserved bonus in the end, but also seeking to teach the hard working world their wickedness.