In the US if you give a politician money in exchange for voting against a bill, it’s illegal (it’s called “quid-pro-quo” in lawyer terms)

But if you just donate money to the politician, his family, or his campaign, without requesting anything - and then he “coincidentally” happens to vote against the bill which you didn’t want, it is perfectly legal.

Basically, many politicians are regularly doing something clearly unethical and corrupt in a technically “legal” way.