Airlines pretty much everywhere for a long time have been responsible for verifying prior to boarding that passengers HOLD the correct travel documents to enter the destination country and intervening international connections where necessary. What the airlines are NOT responsible for is verifying that passengers have such documents in advance of for giving advice on how to obtain such documents. That responsibility is on the passenger. The ETA process has not shifted the responsibility, it has supposedly automated the process for a portion of the travelling public in that the ETA is linked to the passport.