High 50s isn't actually an issue for any modern CPU I know of

Yeah, that's almost certainly not because of Unity. At most, it could be blamed on C#, if we're blaming the technology. This is an issue with their simulation I would assume. For example, Timberborn is simulating liquids and a population of workers. The liquids are probably the biggest culprit, and there's a reason you don't see many games doing it.

All the games you listed are simulation games though. They are going to be the largest CPU hogs you can get, especially when you use the highest simulation speed possible. At that point, they're usually literally maxing out your CPU and running it as fast as it can process. As another example of this, Paradox games can not reach their highest speeds on weaker systems or later into the games. They run as fast as the CPU can process, which means nearly 100% utilization. It's not because they aren't efficient. It's because you're telling it to go all out on processing.