I’ll note that for real businesses this is just a thought excercise, but it’s one I keep coming back to. What if some less reasonable entity attempted to regulate in this way?
1. Invitation to treat: that is offering services for consumption
2. Offer to contract: fulfilling the invitation by making a contract of terms
If you drop a potential customer at step 1, e.g. having your web-server decline the connection based on GeoIP, would that not constitute reasonable effort? We don't have case law regarding GDPR yet but I would certainly argue that it shows efforts being taken to exclude EU residents.