>>The existing government mandates - aka "laws" - exist as a compromise. They prohibit a company like Amazon from engaging in certain practices, and in exchange, some union practices are prohibited.
There is nothing of note that unions could do, that isn't enabled by contract-liberty-violating labor regulations and wouldn't break the law. Picketing Amazon's premises, and beating up replacement workers, as the illegal strikes of the past did, was justifiably punished by the state before the labor regulation era, and for that reason, unions had very little power.
All the power they acquired came from laws that abridged the freedom to contract.
>>The economic power of the Boston Journeymen Bootmaker's Society came from the ability to quit - collectively.
Industry would gladly give unions the power to collectively quit, if it meant they too would have their contract liberty restored, so they could choose to not employ unionized workers, or to replace them without government punishing them.
>>I'll counter when a decidedly not benign - the Ludlow massacre, where companies worked with the government to attack striking coal workers, including firing MACHINE GUNS at them and their families.
This leaves out a seminally important precursor to the attack on the striker's camp:
https://en.wikipedia.org/wiki/Ludlow_Massacre#Strike
>>When leasing the sites, the union had selected locations near the mouths of canyons that led to the coal camps in order to block any strikebreakers' traffic.[17] The company hired the Baldwin–Felts Detective Agency to protect the new workers and harass the strikers.
"block any strikebreakers' traffic" means viciously attack and sometimes murder strikebreakers, who were there to replace them.
The strikers were a violent force, engaging in aggression. The only basis for their actions is a victimhood narrative that argues the employer and replacement workers do not have a right to their contract liberty when workers strike. If you accept this illiberal premise, then of course any violence that strikers engage in is justified, and any response is a "massacre".