Question:
For instance, I took a train from Paris to Amsterdam, and the conductordidn't even come by and check my ticket and passport until we were inBelgium (and had made many stops). Ditto for the return trip.

Aren't the countries involved all part of the Schengen area, meaningyou don't need a passport at all to travel between them? (Or was thisfurther in the past?)

Answer: There is generally no argument. Even the calls to the police are veryseldom necessary : people either pay or give an ID to the conductor.