Why not China Embassy in Bangkok not giving Multi entry 12 month validity tourist visa to foreigners

I have US passport. Is there any policy? I wanted to apply for Multi entry 12 mon. Validity since the fee is too high. I live in Bangkok and within a next few months I would like to visit more cities. IF I have single entry visa going out from Bangkok to Beijing, Beijing to Shanghai, and returning back from Shanghai to Bangkok. Is this single entry works for this itinerary?