The corridors I mentioned are perfectly fine HSR corridors, the population numbers and distances are great for HSR, perfectly suitable. That is absolutely not the propblem. Developed countries would have already HSR along those corridors, heavily used HSR, that is transformative for the places along it.

The problem is not getting the land, the problem is politics and legislation that is hostile to it and as a consequence it is nigh impossible to get that land for critical infrastructure like that (hostile legislation is also the reason why multiple the times of construction costs have to be paid for non-construction expenses, not even counting land acquisition). Curiously enough it is not impossible to ever widen highways or even build entirely new ones.