Very intresting read about rights - but please remember, FedGuard writes about Belgian law and rights Whereas they might be very similar in other European countries, there might be/are considerable differences both in theory and practice and even more so in procedural law. Warning - IANAL.
At least one EU country's police is known to sometimes interrogate suspects first as "witnesses" where they are obliged to tell the truth or else they commit a crime. This is not something one would meet at an airport customs check, though.