Historically, socialism grew, at least in a significant part, in response to the exploitation of workers and the extreme wealth accumulated by factory owners after the Industrial Revolution. Keir Hardie, the founder of the Labour Party in the UK, was a leader of a miner's union who led strikes. Not all of Labour's early leaders were as militant as Hardie. Arthur Henderson, Labour's first Cabinet minister, was a trade unionist who wanted to use strikes only as a last resort. Despite this variation in views, socialism is strongly associated with the rights of workers and the freedom of trade unions
Historically, trade unions have a strong relationship with the Labour Party in the UK:
When the Nazis acquired power, what was their relationship with trade unions and the rights of workers?
People who believe that the Nazis were socialists may argue that the Nazis replaced the trade unions with a union of their own, the German Labour Force. That's true. However, as well as eliminating independent trade unions, they also eliminated the right to strike:
Some trade union officials were beaten and tortured by the Nazis:
We've seen that socialists vary in their attitude to strikes - some use them enthusiastically, others reluctantly as a last resort. However, considering the strong historical association between trade unions and socialism, we'd expect socialists to protect the freedom of trade unionists, not to ban trade unions, outlaw the right to strike or to have trade unionists beaten, tortured, monitored by secret police or murdered.