I noticed a lot of the California headlines about this have painted it along the lines of "Evil Trump administration killing California high speed rail!"
The reality is, though, that California botched this project. The Federal funding was contingent on California making progress, and the amount of funding was sized for the size of the project.
California has made little progress, and the size of the project has been reduced. It's only fiscally responsible for the feds to take back the money. Just like if you promise a VC a million users in the first year, but only deliver 10,000 they're going to look at you sideways.
FTA: Federal Railroad Administration (FRA), said on Thursday it had canceled the funding awarded in a 2010 agreement after it said the state had “repeatedly failed to comply” and “failed to make reasonable progress on the project.”
Fortunately, high speed rail is making (slow) progress in other states like Florida, Illinois and Texas. Hopefully the money can do some good in those places.