are you sure? Seems the opposite is true. Low rolling resistance train wheels have pretty stiff sidewalls.Add to the pros: shorter stopping distance.
Add to the cons: Narrow sidewalls are stiffer which increases rolling resistance, even if same width. Noisier too.
of course I'm serious. It is obvious that underinflated tires with less stiff sidewalls have a higher rolling resistance than overinflated tires with stiffer side walls.Train wheels do not go over bumps, no need for compliance. No passengers would be able to tolerate solid steel wheels on roads, not to mention the lack of any braking or handling capability on roads. Are you serious, or just trolling?