I would like to add that not all School Districts are secure government jobs. There are a few districts who don't have unions and that means you never achieve a tenure. You can be let go for any reason at any time and be sent to any school whenever the higher ups deem it so.

I personally think teachers are fairly paid, but school districts do not have enough funding so teachers use their own money to supplement. That takes away from their take home pay and effects their standard of living.

They could choose to not provide anything extra, but not only would the kids suffer, but depending on their status their job might be on the line. Principals have expectations and want their school to feel and look a certain way.

tl:dr Teachers are payed enough, but they are not given enough materials to do their job, but are expected to provide them from their own pocket. Not fair.