A former Wagner mercenary in July told Euronews that while he served in Ukraine one of his main duties was to ensure Russian conscripts - “barely 21-years-old” - would not run away, as they were so reluctant to fight.
Doesn't this compare apples to oranges?
One is an aggressive war. People are shipped into Randomiskan without clear indication what's going on, why they should be there and they are supposed to die for the glory of the state. Sorry, but that's when everyone wants to run. That's also distinctively different from WW2, when concrete evidence of mass murder in occupied europe was available.
The other would be a defensive war. An outside aggressor wants to wipe out your culture and accepts killing or deporting anyone you consider important in your life. Putting it like that, WW2 was very much a defensive war from the allied side. That's a very different motivation.