> And an advantage of high speed trains is they can accelerate very quickly.
They really can't.
They accelerate reasonably quickly, but doing so any faster uses more energy and also starts impacting passenger comfort. People would like to have a cup of coffee on the table without hot liquid sloshing out onto their laps.
They absolutely can. They're obviously limited by passenger comfort as the other commenter said, but the difference between an Acela and a Northeast Regional in acceleration speed is obvious.