I believe unions are necessary in a world of humongous companies. That is because, in case of disagreements, an employee's prospect (losing 100% of their income) is a much worse negotiating position than a large company losing <1% of its workforce.
Many unions soon get corrupted and get in bed with the government (or atleast one side of it). Here in slovenia, many worker unions were against the lowering the taxes on paychecks (higher net with same gross pay), because their political parties were against those, even if the workers themselves would benefit from those. We also have some areas (eg. a government rail company), where you cannot even get a job, if you…
Seems to be quite a lot of context missing. I think nearly everyone agrees they want to pay less taxes and take home more money. Now if lowering taxes does not result in more money then you don't need politicians and unions to make that case.
I'm guessing lowering taxes would result in more expensive, privatized services and voters figured that wouldn't work.