> state-imposed restrictions on businesses to give unions a monopoly over their workforces
That's not how all unions work. That is how the worst ones are implemented in the US, imo. eg govt unions, teacher's union, police union, NRLCA vs UFCW or Airline unions (eg https://www.swamedia.com/pages/contracts)
That's how laws relating to unions and collective bargaining and striking work. You cannot negotiate with other parties once the majority of your employees in a work unit vote to collectively bargain. That means the union gets a monopoly over who you can negotiate with.
Similarly, you cannot fire and replace unionized workers who strike, which again means the union is controlling your company and determining who you can employ.
