For many years it was possible to arrive at T1 CDG and finish out in the street (sans luggage) without ever seeing immigration or customs - I think I did it 3 times..................... I think that was a signage problem allied to lack of supervision on one important door...............
What was weird was that they knew all about it - when you went up to a guy in Customs and explained he'd shrug and take you through the "behind the scenes" bit of Immigration and leave you in front of Immigration.. most odd