There are plenty of game dev companies where employees are treated well (I work for one of them) but "game company treats employees like human beings" is not an interesting enough headline, so you don't tend to hear about it.
But in spite of working for a really good studio right now, I recognize that many people are not (I've also worked with ones that were middling at best), and unionization is a great step towards getting better conditions, especially for artists and content people. Engineers tend to get the best treatment since toxic management know they are more expensive, harder to replace and have more opportunities across a variety of industries. Conversely, if you are a 3d artist (just as an example), there are only so many places you can work, and unfortunately you are often considered more disposable.