I suspect Chinese bought off local politicians, who let Chinese have their way.
BINGO!
Back in the 1980's, the EU & Great Britain (IIRC) were providing funding for a Yugoslav company to rebuild. Kenya's major (only) highway from Nairobi to Uganda. When I stopped by to take a look (back in the late 1960's I inspected road construction and was now curious), they were beginning to pave using 1.5" asphalt over a compacted earth base. NO gravel and NO soil cement!
When I asked the Yugoslav construction superintendent about it, his reply was "Go away, don't bother me."
A year later, that section had a detour due to the pavement breaking up.
Of the total "cost" to build the road, probably half went into materials, equipment, overhead and labor. 10% for legitimate profit. The rest went as graft, both to government officials and to the contractor