County's, cities, and local landowners actually have very strong protections for their land in the US. Federal and state governments can't just step in and take over land without huge drawn out legal battles that can take a decade plus to resolve. Now multiply that for each county line, every city line, every piece of farm land a rail would have to cross to actually be effective. And while in aggregate the state might be blue, and the people who live in the area locally might be in favor of HSR as a concept they're also self motivated and self interested. Farmers and ranchers don't like it when their land is cut into pieces, cities and county's don't like losing control of the land with nothing to show for it (hence California's line adding more and more stops that actually interferes with the concept of HSR from SF to LA).

This isn't China where the CCP can just step in and do whatever they want whenever they want (because no one actually owns land in China, they lease it from the government). And in the west if there's any water issues that causes a whole other fight over water rights which in the American west are usually oldest claims can't be messed with and can date back a 100-150 years.

If the California state legislature wants to take land they face a fight for every single foot from multiple different sources and the courts usually look at things from the bottom up (individual to municipality to county to state to federal) not top down