In my youngin years, I worked for a major tech company ... lasted about 9 years. We had about 1500 employees across the country, no union. Each year, everyone underwent individual performance evaluations, not as a collective, but based on our contributions, experience, achievements, and where we wanted to go within the company.That is why unions renegotiate contracts at intervals, both sides get a new chance to negotiate, because circumstances change, price of living goes up, etc. Without a union it’s far more difficult to any kind of raise or bonus, and when you do it’s at the arbitrary whims of your boss or HR. I’ve worked in big tech, without a union you have very few opportunities to make more than what you got when you started.
Although there were occasional "manager challenges", I generally didn't have anything major. Each performance eval determined my salary bump based on my achievements, responsibilities, etc ... if I wanted a higher pay I was told what steps I needed to take to get there - be it through further education, getting more IT certs, or assuming more responsibilities. I put in the work, studied late and somehow climbed the ladder, I know we're not all the same, maybe I was lucky ... but my understanding was and still is; you want to make more, you put in more.