The most painful part of high-speed-rail, particularly at higher speeds, is the land acquisition costs; minimum curve radius grows exponentially as speed rises, so costs escalate as speed gets higher. China cares far less about compensating property owners for fair value, which is why they can engineer such high speed lines in the first place.

We are talking about the difference between 217MPH and 200MPH. The total travel time saved between Boston and Washington by an additional 17MPH is a whopping six minutes with the generous assumption that you start right off the bat at top speed and maintain it the entire trip. If saving six minutes will cost billions or tens of billions of dollars, why bother with such a marginal improvement, when you could spend those billions on literally anything else from housing to healthcare to upgrading the power grid?