I have worked several union jobs, collective contracts usually don't touch the promotion process. If they do they often give automatic promotions after X years where X is still a fairly high number. And obviously this is not a great strategy for many reasons.

Negotiations about yearly pay raises are common but these are in the 2-5% range. Even non unionized big tech companies usually still give these yearly adjustments but its nothing compared to the 20-30% you can get when you level up.