All countries/central banks issue banknotes with serial numbers for a reason... there is no exception.
This is a long-time international practice, so I'm surprised you've never heard it before
Don't make up things about me. Of course I know what serial numbers are.
During a bank robbery, if a robber has taken the bait money, details of this can be passed on to the police. If the money is found in the possession of someone, or used to purchase goods, this can make it easier to find the suspect of the bank robbery.
That's not the same as blaming innocent people. I'll end this discussion here, it's far too off-topic.
I didn't make up anything, you insinuated that this isn't a common practice in many countries.
This isn't a "police problem" as you claimed, it happens everywhere:
https://www.fbi.gov/history/famous-cases/charles-ross-kidnappingAnd don't make up things I never said. I said they will interrogate you, not blame/jail you:
As soon as that "tainted" banknote enters the banking system, you're fucked. They will freeze the money and the police will interrogate you where you got it from.