Visiting that site from Canada I get this message:

> The OptOutPrescreen.com website is only accessible through ISP's (Internet Service Providers) located within the United States and its territories.

Rarely see that on non-media sites.

Can someone explain what it does?

It doesn't do much that is useful in the uncle's situation.

If you register for it then you won't get unsolicited credit offers from companies you don't have an affiliation with. So American Express can only go pulling random people they aren't affiliated with a score of over 700 or whatever and send card offers only to people who haven't opted out.

However, it doesn't prevent companies from marketing credit offers to people they do have an affiliation with. So if you have an AMEX card then American Express can market other American Express cards to you even if you signed up for prescreen opt out, and your bank can market their cards to you, and your airline rewards program can market their cards to you, etc.

That website was set up as a result of the Fair Credit Reporting Act (which also allows people in the US a free credit report once a year) which only applies to Americans.

What's the risk of a non-American person looking at the website?

Consider that they can probably do so simply by using a proxy located in the US, or while visiting the US.

"Legitimate" users don't notice, casually-interested people get annoyed, and fraudsters work around it.

It doesn't solve anything and I wish people would stop doing this.

To prevent confusion. If a Canadian looked at it they may believe that it applies to Canadians.

I had a more cynical view that it was so the credit card companies had the fewest amount of people opt out. They could have made that site apply to anyone worldwide but that would hurt themselves.

No, you're not clear on your understanding, that site isn't run by credit card companies, it's run by the three credit bureaus.

Basically, credit card companies (and insurance companies) buy consumer data from the credit bureaus to send unsolicited offers. That site is for you to register with the bureaus that you don't want your credit report sold in that way. That's how come companies can still send you unsolicited credit offers when they already have your information from elsewhere, such as from your bank account or frequent flyer account.

I don't know which, if any bureaus operate in Canada or how that are allowed or not allowed to sell your data. That particular site gives you specifics information about American law (FCRA), and how things work in America with credit bureaus information sharing - it's completely irrelevant for Canada.

I don't know what we have, but I know that apparently, having a lawyer and power of attorney tell a credit card company to not send credit cards wasn't enough.