Unless this was changed later, I think a major issue was that not only was the governor changing their money without negotiation, he was also refusing to negotiate over hours and working conditions.
To clarify...
Act 10 was Walker’s budget reform. Under it the law allows state, school districts, and municipal employers to ask state employees to contribute a minimum percentage toward their health care and their pensions. It withdrew the privilege that the unions had in ‘collective bargaining, limiting their bargaining to wages and limiting those to inflation. Their working conditions are still protected by state civil service laws.
Keeping the record very clear, Walker did try to negotiate with the unions before the Act 10. They called him a ‘slave master’ for asking for these concessions.
What really torqued the unions was that Act 10 also relieved the state of the responsibility to collect union dues. This stops the easy income of big labor and over time will lead to a drastically smaller income. That is why they are on the warpath.
Stopping big unions allowed our property taxes to go down. It will also lead to improvement in our schools.
Oh I forgot one more element. The teacher’s unions had used their collective bargaining to force school districts to use the teacher’s union’s own health insurance company. This company charged about 1/3 over market rates. Getting rid of this coerced sweetheart deal saved Wisconsin taxpayers in the neighborhood of eight hundred million dollars.
Those are the major issues.