The entire point of the article was that we did put cocaine in soda at one time, and that did not stop because of the social problems that ensued. Just like the people of Andes have not stopped drinking their coca tea because of some hypothetical social problems it causes. A coca-infused soft drink need not have enough cocaine to cause any sort of "high," any more than a caffeine-infused software drink has enough caffeine to cause a high or a therapeutic amphetamine dose has enough amphetamine to cause a high.
Don't let US government propaganda sway you when it comes to drugs. Cocaine is not the cause of social problems, not in the United States and not in countries where it is widely used. Cocaine prohibition causes more social problems than the drug itself (not that the DEA or ONDCP people would ever admit it).