My brother just landed in the USA at Newark and told there were separate queues -- one for those who have entered the USA within the last two years on ESTA and the other for first time visitors. Why is this separation in place?
That would be due to the APC kiosks of course, which, at certain airports, are only available to VWP nationals with a previous entry (i.e. having been fingerprinted and photographed). In addition, depending on the airport, it might be a requirement that a previous entry has been made on the currently held passport.