well I dont think china have a problem manufacturing body army and issuing it en masse, about a month ago about 1000 bulletproof vest, several hundred kevlar helmets and backpacks(4 million dollar worth of stuffs I believe) were donated to the JDF(Jamaica Defence Force) as a move to strengthen military ties. If they can give away armour like this I dont think cost is the problem, it is just not practical to be purchasing so much of the stuff if peacetime.
In contrast the JDF and police here, albeit small(20,000 in total), faces danger daily from some of the toughest gunmen in the world armed with small arms in urban areas, thus they need to maintain a stockpile of these in reserve.