There would also be problems when people travel (either as tourists or to permanently move); what happens to their 'old' data, or their 'new' data when/if they

There would also be problems when people travel (either as tourists or to permanently move); what happens to their 'old' data, or their 'new' data when/if they travel back? So-called 'edge cases' become big problems when you have a large number of users, and fines/penalties are based on corporate revenues (rather than damages).