We also have a policy of ensuring that we have no single point of failure when it comes to technical or institutional knowledge. Our tech work community is really good at ensuring that we keep others in the loop and document everything.
Non-management positions are subject to a union collective agreement. The money is good mind you but there are no raises outside the pay grids.
Are you taking leadership responsibilities? Leading your team, mentoring others, representing your team in broader meetings with other teams, helping with planning, etc. Doing that stuff probably means you stop doing technical stuff.
I have also taken the company recommended leadership courses.
I agree with the others that sometimes the path for career advancement can be to move on elsewhere.