> unions are for fighting for better conditions for their workers regardless of gender or race

Regardless of, but not blind to. Different workers do experience different conditions because of race and gender among other things, and unions need to account for those differences not pretend they don't exist.

> I could in no way trust a tech Union to actually fight for me and not against me

You probably didn't mean it this way, but this strongly implies to me you are knowingly doing things that someone who cared about racial or gender equality would feel like they would need to fight. Why is that?