Not biased.... it's the system lah.
In my son's school, the children whose parents are grassroot leaders, industry captains, business leaders, super scale civil servants and lawyers are NEVER punished even if they had broken all the school rules.
This was explained to me by the chairman of the clan association that founded the school after discussion of some matters during the PTA meeting.
The principal and school staff are reminded not to offend the 1st 4 category of parents..... while the school advisory board made the decision on the last category after they were sued by a lawyer parent and had to fork out a substantial amount of money to settle out of court.
The chairman further informed that this is the common practice amongst most schools.