Gene,
Not for sure what you are saying when referring to EOT lights on the caboose. We are basically talking about the device that RR's went to when they did away with the caboose. With that said, Federal law requires a light on the rear of every train between one hour before sundown and one hour after sun up. Railroad law requires that "every" train has to have a "marker" to indicate the rear of the train. A caboose does not necessarily mean the entire train has passed as one could theoretically be shipped to another location for repairs, modifying, shortages etc. This rule is to protect local crews and MofW employees who are waiting for a train to pass before entering or fouling the main line to do work. As they inspect the passing train they must look for the marker on the rear car. If they see a marker then they know the train is past and will not be returning and can go to work. If they do not see a marker then the train has not technically passed them and the portion of the train they saw go by might be returning, say after setting out a defective car or a block of misrouted cars at the next location. These are all old rules from days gone by prior to modern communication systems but the railroads have decided to leave them in affect in case of communication failures. Lives are at stake and the railroads ALWAYS go for the most restrictive of the choices available as there is no room for error.
Since passenger trains have people involved they are even more restrictive with special rules just for them. For instance, after leaving a station, a passenger train must make a "running" brake test. Without an EOT device to signal the decrease of air pressure on the rear car the engineer would have no way of knowing if the brakes worked on the rear car or not so I would have to say that a passenger train would have to have some sort of telemetry device nowadays. In the old days they of course always had marker lights and plenty of crew members to see to the compliance of all the rules. They communicated with each other and the engineer thru a "signal cable" that ran thru every car to the engine.
prof
