The guidance we have received is that if your business is not located in the EU, not targeting EU countries, you don't have parts of your site translated to languages spoken in EU countries, and do not have an EU-based domain name extension, your EU traffic is considered incidental and GDPR
probably does not apply to you. But, as with everything in the GDPR, that is extremely murky. This law is subject to unique interpretations and degrees of enforcement in the courts and regulatory offices of 28 distinct countries. This is why we simply chose to block EU traffic - there's no need for us to take on the liability of EU traffic, and
hope that some country over there doesn't need fines from us badly enough to decide that article 484208408 makes us subject to it.
With regard to enforceability outside the EU, that is anyone's guess. If you're in the US, there are already mechanisms that allow for the domestication of EU judgments in the US. Once domesticated, the judgment would have the same force and effect as if it had been issued by a US judge. However, the treaties that allow this are very complex, and allow for a large number of exceptions. So it would be up to a US judge in each specific case to decide whether or not a judgment for a fine issued under the GDPR can be domesticated. There are currently no treaties specifically relating to GDPR in the US, and I'd imagine there would be (very welcome) strong opposition to such a thing.