Not at ALL surprised....
Having lived in China for 4 years, married to a Chinese lass, it is absolutely no surprise to me that this has happened, yet again.
With next to no Social Security for anyone (other than the Party Elite), in general the people there have to do whatever to make a living, and believe me, there is NO other society on this planet that is as Capitalist in their very being than the Han Chinese (majority ethnic grouping).
Given that their economy is in dire trouble (internal debt is at crazy levels), a tax regime that does not support the local or regional governments, and inflation ramping up at levels that would set alarm bells rining long and loud in any other country, the average person in China has to do WHATEVER to try and increase the yield of their produce - Clen for their pigs, EASY FIX.....Melamine in the milk for higher protien yield, EASY....
Get the picture?
The article in the LA Times is pretty much "on the money..."