Why is the govt in charge of the railroads?
Railroads were intertwined with government entities from the very first. To open the western territories, railroads were granted an enormous number of land sections in the land plats for the layout of their tracks, and they then turned around and sold these sections for their enrichment, founding towns and bring commerce to regions that only then were beginning to be settled. The Post Office used the railroads as their long-distance delivery vehicles, and while not all railroads gained from Federal assistance, many were founded and supported by the states themselves, like Illinois Central, among others. Railroads have always been regulated and yes, subject to taxation, sometimes at an extremely unfair rate, by local taxing authorities. So yes, the history of railroads and government at all levels is woven in innumerable ways. “Special relationship”, doncha know.
Because the wanted to be. It’s also in the constitution, allowing congress to regulate interstate commerce.