Why isn’t "Democrats would never get away with this" seen as a problem for the left?”

I hear people say things like “if Obama (or anyone left of Republicans) did what Trump did, there would be hell to pay.”

Why isn’t that argument taken more seriously by people on the left as an implicit admission that the left is politically weaker or less effective at wielding power?

If one side “can’t get away with” actions that the other can, doesn’t that suggest a real imbalance rather than moral superiority?