I am surprised to see Chinese citizens wanting to get US PPL licenses. The pilot shortage in China does not require anyone to show up with a US pilot license to ask for work. What is driving this phenomenon?
Plenty of people train in the US as there are many flight schools and the costs are very reasonable compared to other locations. Often there's a mechanism to get a license in one's home country on the basis of the US license, or just use the hours and take the practical test in their home country to get a license there.
Additionally, having a US license allows you to fly a US registered airplane, it doesn't matter where in the world it is located, so it could be that many of the airplanes they want to fly have US registrations.