The US has a lot of charity scams and dubious NPOs collecting cash. There’s news about fraudulent GoFundMe’s pretty regularly, for example.

Finland is probably too far the opposite direction, but the whole sector could use a lot more scrutiny over here.

It seems like a lot of charities in the US are just a way for the wealthy to avoid paying taxes or for the founders to become wealthy

Yes, it’s not uncommon to have do-nothing NPOs that associate themselves with a noble cause and then spend most of their funds on one or two people’s salaries and perks. This is why apps like Guidestar and Charity Navigator were invented.

The IRS doesn’t seem to give these orgs much scrutiny unless they’re egregiously bad or become a big news story.

The IRS has been co-opted by the very wealthy. The IRS spends way more resources auditing the very poor than the very wealthy

Grifters calling or walking door-to-door and asking for money, for some made-up charity or organization. Especially targeting older people.

It's extremely frowned upon to begin with, but at least the laws make it illegal.

(Not that it necessarily hinders those that really want to scam someone. Some of these BS "organizations" just contract their work to foreign call-centers. Every year a lot of young European people are lured to some low-cost country in southern Europe, where they'll have to work for some call-center at below minimum wage - and these centers will sometimes work for anyone...)