Life as a teacher

Is it true that life as a teacher always have its up and downs?
Whatever the teacher does seem always to be at the scrutiny of students.

Why is the teacher not fair?
Why did i get less marks than i deserved?
Why so many homework? (okay, this has been the #1 complaint..but got used to it)
Why did the teacher hold us back for extra lessons?
Why did the teacher nag at us?

But why are there no complaints when:

Why did the teacher give me more marks than i deserved?
Why did the teacher let us off early?
Why did the teacher give us sweets?
Why did the teacher not give us homework?
Why did the teacher let us off for not bringing notes/assignments for this period?

What is the real issue behind all these so called questions?
Time to ponder, time to reflect, time to become more mature...