Very true. I worked in the public sector for 40 plus years. People are quick to condemn and very slow to praise. I've changed tires, pulled vehicles out of ditches, found missing children, boosted thousands of batteries - in other words gone out of my way to help people. Very few, like half a percent took the time to write a note of thanks or contact my supervisor. On the other hand when the public is dissatisfied they don't hesitate to complain - in writing. Often times the complaints are embellished for greater effect.
It beats one down. I like people and turn the other cheek but working for an ungrateful public beats most people down to the point that they stop making an extra effort and just do their jobs.
Unfortunately that's the human condition.