>>1939243There are a lot of operators that lease trackage rights from other operators. It's particularly common with shortline freight railroads and heritage/tourist railroads. But it's also common with big railroads.
Pic related. They own the blue lines, have trackage rights on the dotted lines and lease/rent the yellow. This gives them access to more track and kilometers, but they don't own it all.
Amtrack, the largest passenger operator in the US, owns very little track of its own. Most belongs to major freight railroads but there is a federal law that ensures they get prioritized over freight traffic to ensure passenger trains aren't any slower than they already are.
https://en.wikipedia.org/wiki/Arrangements_between_railroads 