On METRA and the CTA putting your feet up is verboten, too. Push it far enough and yes, you’ll be arrested.
L
Can't speak for the CTA, but I ride Metra every Monday - Friday. Have been since 1988. I routinely rest my feet using the empty seat in front of me. I hang my feet OVER the seat so that my shoes never touch the seat, my ankles and calves do. When I'm on a late train (anytime after 7pm) I've occasionally taken my shoes off and put my feet on the seat to rest & nap on the way home. I've never received so much as a comment from any Metra conductor about doing so.
What you WILL get thrown off the train for is being drunk & disorderly and being hostile/belligerent to other passengers or the conductor.
That's been my experience for the last 27 years on Metra. Note that I take the Metra Southwest Service train and it's seldom full. There are almost always plenty of empty seats on the train I ride in the morning and evening.
Nothing worse on a snowy day than some a$$hole punk on the second level putting their feet on the seat on on the rail and dripping everywhere.