Maybe other leagues pay less, but mean NFL referee salary is about $200k. I suspect it wouldn't be cheap to pay one of them off, since getting caught risks prison time, damages, and millions in future income lost.
City councilmembers in my city are paid about as much and the price for them is apparently only like 20-50k cash for quid pro quo that could land them prison time, according to the FBI investigations from the ones who got caught at least. That's nothing compared to what could be gained.
You have to look at it relatively. Fine the ref is getting paid $200k, but the owners in the box seats are worth billions, the gamblers in the front row seats are worth hundreds of millions, and the players are worth tens of millions. Any of those guys can slip the ref a life-changing amount of money if they really wanted to.
