Outside of the areas West of the Mississippi where the railroads crossed public lands the US government wanted to have settled by farmers, where did railroads get FREE RIGHT OF WAY?
You are now being silly.
Eminent Domain has been in the US Constitution because it has been known since the very first days of man that contiguous land was required for moving products from point A to point B. You are being silly because while you obsessively focus on the rails you seem to forget about every road from farm-to-market to interstate, you forget about every canal that was dug, every pipeline laid, every high powered electric line.
In the late nineteenth century, you could walk for days without seeing anyone or anything, so a forty foot wide swath going through mostly Indian country was nothing. Besides, how on earth did you expect the farmer and rancher to get their product to market without roads and rail roads? How do you expect them to get their tools, clothes and other materials from the industrial East without roads and rails?
It was the railroad, not the Colt revolver, the tamed the West. And here you want a retroactive penalty against the lifeblood of this country.
When the railroads came through (once they'd been invented) they had to acquire land the old fashioned way ~ either someone traded it for stock, or they paid for it. The government wasn't giving it away at that time.
"Free Land" was the claim but that idea is simply not supportable East of the Mississippi.