You can reclaim TSFs, though. It is certainly not easy, but it is doable.
https://m.youtube.com/watch?v=YpF-SE3AwEo
This rec is coming up on 15 years old, and is the top of the TSF. The sides of it date to the 90s or earlier, and look pretty good. Trees were about 20 ft or more tall on the sides the last time I was there. The top is shoulder height.
The primary issues related to the cost of placing a cover that is thick enough to entomb the tailings (assuming they have metal leaching potential) that plant roots won’t compromise. The other problem is geotechnical stability issues if you use trees to revegetate, as their roots can go deeper or you get blow down that creates a hole in the reclamation cover, creating an erosion channel over time.
Oh I’m with you on the prevention side; especially with oil sands - it’s a marginal product at best with huge env. Damage.
For reference, they don’t backfill because it’s stupid expensive and the operation wouldn’t be profitable. You would also likely have major subsidence issues.