Most people don't like change especially when they have gotten away without working for so long. Kind of like Texas teachers and the Texas Teacher's union. Same flavor different country.
As for killing people, the protesters severely injured 50 federales. It works both ways.
I guess a lot of people just don't know the story. Not much to have a dialogue about, the senate and house of representatives were the ones who voted for it, not the Secretario de Educacion Publica.
The same as any senate in any country. People vote for them and when they turn out to be rats nobody has the huevos do go back kick them out.