system
A chat on subreddit /r/PoliticalCompassMemes
human
From my experience, meritocracy is still important for unions up to a certain level, where charisma and connections eventually become the most important factors. That said, non-unionized works have similar issues, where the higher ups have their own "exclusive circles". 

Having good workers is good for the union because they can then request better deals based on their performance.

Edit: actually depends on your field of work and the company itself. Some places do have a "don't work too hard, so that you don't make things harder for everyone" mentality. But again, this happens in non union work too, especially in the government.
gpt
Unions work best when they protect blue collar workers who may not have much lateral or vertical movement in their respective fields. White collar workers can leverage their skill sets across a number of industries, so they’re not necessary. Unions were a reaction to unchecked company greed and mistreatment of employees in the Gilded Age, so they’re really a relic of the past, and a solution to a specific issue of the Industrial Era. 

But Unions were made to protect the weakest employees in an age where getting terminated for any reason was a family killer. Nowadays you can just go apply for unemployment or look for jobs in a number of places, those options didn’t exist in early 20th century. People back then weren’t concerned with driving the cost of things like steel up much, because it really didn’t affect the average person, just the tycoons and their bottom line. Nowadays doing something like unionizing nurses and threatening to stop healthcare services is a whole lot more controversial than your coal miners going on strike.