What makes milk suppliers put chemicals in milk products that they know babies will use?

Many of those only interested in the quick buck, are quite prepared to do anything to get it. They rarely think of the consequences because their vision is blinded by absolute greed. They're not interested in making a name for themself. There's not enough time for that. Once the word gets around they just change their name, number and email. Short term thinking prevails in such an environment.

The English teaching recruitment business in China attracts many of such.