I'd be interested if you could ask your users if they are _not_ a EU resident. Only if they click yes go ahead, otherwise show that you will not serve them. Probably 90% would learn to click the "Not from EU" button. Who should hold you accountable for false user input in that case?
In the case of Facebook, people people upload photos with gps data, attend events that have an address... No judge would accept the 'but they said they weren't a EU resident' argument.
