Sure, one needs to start somewhere, and it is likely infeasible to organize majority of Amazon warehouses simultaneously.
But what leverage over Amazon would such single unionized warehouse give to labor? And AFAIK without good leverage Union cannot negotiate anything significant for its members, why members still must pay their dues to the union, ending up worse on the balance.
Wouldn't successful unionization of the single warehouse serve more like an inoculation from the organized labor for Amazon? What parts of the picture do I miss here?
US has enterprise collective bargaining (as do UK and Ireland). Most other western countries have sectoral collective bargaining as the main method, augmented with national and enterprise bargaining.
The main drawback of US type system is that it pits unions and companies against each other more than necessary. It's more adversarial because companies that are not unionized get competitive advantage over nonunionized companies.
1) the threat of a good example -- see how the US still treats Cuba, etc.
2) 'labor' is crushed in america. they/we are nothing. so, any tiny effort, however misdirected, ill-advised, etc. -- is akin to Chinese people protesting in Tiananmen Square -- brave, but not likely to end well.