It's because this site offers services to, and captures personal data from, members in the EU. If an outfit captures personal data of EU citizens, then it is bound by the GDPR. Many organizations are setting a blanket policy because it's easier to implement one global policy than piecemeal around the world. Your membership dues has a choice whether to agree to the policy.
Looks like ACMOC just squeaked within the deadline of 5/25 - good job Bruce

Don: acknowledged. But you can do something about it if it's important to you.

A key point here is that any organization that wants to collect private data on EU individuals has to abide by EU rules. ACMOC is a U.S.-based club but collects personal data on EU citizens. Similarly (and I'm hoping you'd see that this is the same situation), any organization that wants to collect private data on U.S. individuals has to abide by U.S. privacy rules, regardless of that organization's base country. Turns out that EU rules are pretty much a superset of U.S. rules. To avoid the application of the GPDR rules to ACMOC, the club would need to not allow any EU citizens to sign up and be members (and the club would have to enforce it in order to demonstrate compliance - this would be an expensive undertaking, and likely not seen as a worthwhile use of precious funds by club members). The practical effect of the club's policy is virtually nil on members - the club already has member personal information so essentially all they're doing by complying with the GPDR is agreeing to keep that information safe (there's a bunch of regulations behind the word "safe" but that's the basic intent). That's really no different from complying with U.S. data privacy regulations.

If you feel that it's not where the club should go, you could put forth a motion to the club to disallow EU members - I'd guess it would be an unpopular motion (I wouldn't support it - I like that we have a wide variety of members) and unlikely to succeed but nevertheless you could give it a shot.

Hi Bruce,
yes it's a valid question and your admin and Don are both right to question it - we should always be informed about what the club does and why. I think part of the GDPR issue is that it wasn't well-publicized here (being as it's a European ruling) so it's likely caught a number of folks this side of the Atlantic short. But you and the team have met the compliance date so we're in really good shape - thanks for all you do!