The only difference is that in places like the U.S., the CBP will pull their guns and then lock you up in cage if you don't pay.
Really? I enter/leave the U.S. three - five times a year (and that for over 45 years), and there has NEVER been the slightest hint of a bribe from anyone. Reporting any U.S. CBP or ICE official of doing such would result in them being arrested with very serious jail time. I doubt if there have been many (if any) U.S. officials even looking like they wanted a bribe. BTW, there are CCTV cameras not just looking at the traveller, but at the government personnel, too.
I have had "suggestions" for which I acted too stupid to understand at several places (Panama comes to mind), but not in Viet Nam.