Amtrak is a private company quasi-public corporation that is bailed out every year by the US government. They own almost none of the track that they run on, except for the Northeast Corridor (where I live) and a couple other lines. They make a profit on the NEC. The rest of the network is owned by freight railroads, who are incentivized to keep their trains slow (freight is very patient) and downsized to reduce maintenance costs. This means trains capped at 79 mph in most places running on single-track lines. Freight companies are required by law to clear the main line for Amtrak, but this law is very shoddily enforced. Delays also beget delays, so if one railroad screws up or intentionally blocks the main line, the rest of the line is also delayed because the time slot is now different. This is what leads to Amtrak often being multiple hours off schedule; for freight "on-schedule" is much more loose.