Exactly and the simple reason why, which keeps these basic economics of bribery working so robustly, is the asymmetric measures of value/cost inherent to the tw

Exactly and the simple reason why, which keeps these basic economics of bribery working so robustly, is the asymmetric measures of value/cost inherent to the two sides of the equation. A government or facebook employee or whomever who has access to some lever worth a great deal will sell access to it for these fairly small sums exactly because the much greater value isn't actually a cost to them. They're leveraging their access to someone elses resources for personal acquisition of a much smaller but to them worthwhile gain. You'd never convince a billionaire to sell you access to something of theirs worth billions by paying them only millions, but, like you said, you can easily convince a senator to give you access to billions in government resources (tax money) for a few million to their personal campaign.