Assumed Success for Things Other Than Physical and Magical Actions

[billd91]

But it doesn't seem nearly as often to apply to social actions, for some reason. I've seen fairly routine bribes require a persuasion check from an expert in persuasion with high cha, which seems just as unlikely to fail to me as the athlete failing to long jump a few feat.

Anyone have thoughts as to why this is? Do you often bypass rolling in social challenges when failure is very unlikely?

I think for a lot of people, even minor interactions are a bit different from getting up a wall or handling things without active opposition because the target is an individual NPC capable of a wide array of reactions. And they're not going to let you simply control the NPC - hence a check to overcome the NPC's will/resistance to simply go along with the player's wishes.
I'm not saying that's necessarily an ideal way to approach it, but I think it's a perspective that may drive the situation you're asking about.