no argument, but the cost must be insane
apparently there are only test runs so far. i would speculate by the crowd it might be:
"On 2 December 2003, MLX01, a three-car train set a world record speed of 581 km/h (361 mph) in a manned run
...
On 26 October 2010, JR Central announced a new train type, the L0 Series, for commercial operation at 505 km/h (314 mph).[53] It set a world record speed for a manned train of 603 km/h (375 mph) on 21 April 2015.[54]"