Amtrak doesn't own much right of way.[1] Only about 700 miles. There are about 140,000 miles of track in the US. Nearly all of it in private hands.

In France, the railroads are nationalized. A new high speed line doesn't incur the similar costs for right of way acquisitions.

[1]: http://blog.amtrak.com/2019/05/why-are-amtrak-trains-delayed...