IMO that was part of an 'agreement' between Mao and Chiang Kai-shek. They both knew the countries infra-structure should remain intact no matter who came out on top. So they agreed to use the allied help for their own needs and ends for post war time.
There was a lot more 'co-operation' between these two than is publicly admitted. They were both using the Americans and British for their own agendas.
That sounds plausible but I don't think it is correct. Scott, who wrote "God is My Co-Pilot" was very supportive of Chiang Kai-shek.
This particular book "Flying Tiger" had a section about the Communist influence in China and that is where I got the quote about the bridges.
I actually got to meet Scott when he was in his 80's and he was in great shape and mentally sharp. I did not get to talk with him too long but did get in some questions about Joe Stilwell, and the State Department. Scott had mellowed a bit but still thought the country was being run by one-worlders, or at least they had a lot of influence.