"Cartels of unions" or whatever are legal in some jurisdictions. See e.g. solidarity action / sympathy strikes. Depending on the country, that varies from "to

"Cartels of unions" or whatever are legal in some jurisdictions. See e.g. solidarity action / sympathy strikes. Depending on the country, that varies from "totally illegal" to "well of course you're gonna solidarity strike, that's how it's done".