Unions are a tool to contain and prevent abusive practices by companies in a free market.
As a result, most union members are going to be pretty anti capitalist in nature, or at the very least against unregulated capitalism. They would much rather have the abusive practices they protest against banned.
The alternatives to an unregulated free economy are either a state managed economy (communist style) or free-ish markets regulated by a government that sets the rules and limits the damages of the competition, by providing both regulations and safety nets (social democracy). both of those approaches require a strong state, which is were you get pro-government and pro-higher taxes.
I guess you could, theoretically, have unions that see themselves as the only necessary opposition against companies' power in a free market, and which see no need for legal protection for their own activities. It's a weird middle point though, and I certainly have never seen a person hold those beliefs.
The strongest unions tend to be government workers because without a free market they have the fewest options. Air traffic controllers work for the FAA or the do something else. Even when their are options like private prisons or schools, when the overwhelming majority of jobs are through a single entity individual employees simply have zero leverage.
Regarding your last point,there's syndicalism, a political theory in which the main organizational unit of society is the union and there's little to no government, everything is negotiated between the different unions representing the various workers. It was somewhat popular around and after WWI, but is pretty much dead now.
As a result, most union members are going to be pretty anti capitalist in nature, or at the very least against unregulated capitalism. They would much rather have the abusive practices they protest against banned.
The alternatives to an unregulated free economy are either a state managed economy (communist style) or free-ish markets regulated by a government that sets the rules and limits the damages of the competition, by providing both regulations and safety nets (social democracy). both of those approaches require a strong state, which is were you get pro-government and pro-higher taxes.
I guess you could, theoretically, have unions that see themselves as the only necessary opposition against companies' power in a free market, and which see no need for legal protection for their own activities. It's a weird middle point though, and I certainly have never seen a person hold those beliefs.