The Amtrak Wolverine service (Chicago to Detroit) begs to differ. And just last week the Lincoln service (Chicago to St. Louis) and the Texas Eagle service (Chicago to Dallas/San Antonio) got approval for higher-speed operation.

Brightline is very successful, part of which is due to having so few stops, something that a public railroad could never get away with politically. The Amtrak trains stop so often that they spend very little time at their top speed.