a) Too young or inexperienced or fearful of reprisal to understand how to advocate for themselves and others; and/or
b) Just unaware that better places to work do exist, and are convinced (much like the thread parent here) that "this is just how gamedev is"
Unfortunately because gamedev is a dream job for a lot of folks they are unwilling to rock the boat because they want to live their dream. That is why unions are a great opportunity for people like this, it gives them some agency to make a positive change.