I am curious, how often workers and unions in Germany are protesting against left wing governments and local authorities ? I mean the left isn't exactly what it used to be in that regard. So I am asking for the sake of comparison because I am having such protests.
Big strikes and protests by workers and unions are rare, at least much more rare than, say, in France. There are strikes going on as I'm writing this, mainly about pay increase in the public sector, so it definitely does happen. If you are talking about major disagreements between organized labor and left wing parties though, I'd have to think hard. The biggest conflict I can think of was against Schröder's welfare reform, but that was over 20 years ago.
When it comes to labor conflicts the thing is that employees who are union members are ususally well-payed. Physical laborers in factories are actually quite well payed if they are qualified. Unqualified bone-breaking work (harvest work, meat-packing, etc) is usually done by Eastern-European migrant workers with very little rights and very bad pay. It's the unqualified, temporary workers - who ususally aren't organized - who work long hours for little money and no security. And when the state, left wing or right wing, takes measures that mainly hurt the unemployed or underemployed the unions won't protest much because that's not their clientel. Unions here are usually against temp workers getting the same rights as people wirth longterm contracts. So there's a two-class system on the labor market. But since there is a serious shortage of qualified staff in nearly every industry (especially, but not only, in the care sector, so nurses, kindergarden teachers, etc) chances are conditions for the qualified will only get better while there is little left of the cake for the unqualified.
The SPD stopped being close with unions decades ago, by now the closest party would be the Linke, but - as you probably know - that party has been in crisis for a while.