I agree security on trains is virtually nil.
A few years ago my family and I rode the train from Chicago to Minneapolis. We were in the sleeper car. The next rooms over had what had to be 4-5 drug dealers. There was a
gun fight between drug dealers and the police at the Amtrak station in Chicago a few days after we rode the train.
That's exactly what I LOVE about rail travel. No having to stand in a long security line, walk through a metal detector, get my carry-on x-rayed, and get groped by some government stooge because I forgot to take my keys out of my pocket. If Amtrak really is seeing an increase in passengers, I'd bet the farm that the lack of security is a reason for it.