Why are Teacher Assistants treated so poorly?

I am a college student and work for DC Public Schools as a Teacher Assistant. I can't believe how poorly TAs are treated throughout the school district. It is the culture of the school system to mistreat their very valuable overworked, underpaid, and faithful helpers. The TAs are with the students more than the teachers. The TAs wears many hats around the school but do not receive the dignity and respect that they deserve. Why is this behavior condone? What can we do to change this culture?