It may be a greedy landlord, but that is likely not the case.
Property taxes seem to increase every year, at a rate of about 2-3%/year .
All other costs such as home insurance, landlord's utilities such as cold water, etc also typically increase every year.
That's inflation and corporate attitude of always increasing profits for you, ever increasing costs that eventually get passed down to you some way or another.
So we are left with two possibilities, the landlord eats his increased costs or passes it down to you.