Originally Posted by
LoganFlyer
2. That said, for someone who's not familiar with the local customs (e.g. a foreigner), how are they supposed to know the difference? They see a sign with a DL logo outside that says they can check their luggage, so they do. There's typically no sign that talks about tipping.
The issue comes up not just for foreigners but also for relatively inexperienced passengers who are locals but generally take it to be the case that those serving an airline's passengers under or near an airline's sign are airline employees or approved personnel. Those are probably often the very same locals unfamiliar with valet service outside of restaurants.