Unions don't lean left, they sprint left.
Only a USian would say this.
What most people in the US are calling 'left-wing' is centrist is most other parts of the civilised parts on this planet. Just because most of US politics are ultra far-right leaning, doesn't mean that anything to the left of that is far left.
Paid holidays, paid sick leave, paid pregnancy leave and a livimg wage are the norm in most of Europe and are considered centrist.