It's called preventative maintenance...a much better alternative to reparative maintenance. Would you want to ride a train where they're strict on eating laws, or a train that constantly has to be cleaned of sticky stains all over?
Apart from the silly gesture that you cannot go without eating for the period that you are on the train, I can't see how anyone would want to eat in an enclosed environment where strangers are coughing/breathing all over you.
Speaking of which, if you're allowed to eat...then so is the dude who brought his egg & atcha sarmies to work. Do you REALLY want that odour climbing up your nostrils?