Because they don’t need to fund Crony Capitalists and the bi-partisan culture of corruption. Plus, they understood the arithmetic that by cheaply connecting the country, it would make everyone wealthier.
Of course, that argument would fall flat in the US. It would be very easy to kill a US rail project by stoking deep seated fears that black and brown people might somehow benefit.
A 6-hour journey in a lie-flat Business Class seat the equal of Emirates Airlines costs $315.
intercst
Perhaps they are funding Crony Communist Party Members?
They’re building infrastructure at 20%-30% of US cost. If they are funding a lot of “Crony Communists”, they’re getting a bargain.
intercst
Market economies have a history of large capital projects leading to bubbles and large losses. Dare I say they were unprofitable too? The British Canal Mania (1790s) the British Railway Mania, the Atlantic Undersea Cable Boom (1850s), the US Railroad Speculation Bubble (1890s), the dot-com bubble (1990s), maybe AI is next. In all cases, and probably in China today as well, the investments eventually boost the economy. The question in the end, as always, is who bears the cost and who gets the benefits.
Of course these are guys also responsible for the “ghost” cities within China.
You really believe China is not corrupt?
Of course not, there’s corruption to an extent everywhere. The question is, 'Who is the world-class corruption leader?"
Saudi Arabia has a pile of corruption, but they balance that with cost-free education and health care for the citizen Saudis.
How do working and middle-class Americans benefit from the bipartisan culture of corruption in the US? I don’'t see any benefit until you’re wealthy enough to forswear any wage & salary income.
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And the ZERO MILE used cars. 
The Captain