Didn't take them long to find out that their modest stream of revenue turned into a trickle as people started doing their shopping outside of Cook County. From The Chicago Tribune:
Cook County Board repeals pop tax
The Cook County Board finished the job on Wednesday and repealed the controversial pop tax, which means soda drinkers won’t have to pay it come Dec. 1.
The repeal was a foregone conclusion after the board’s Finance Committee voted 15-1 on Tuesday, signaling the pop tax would be scrapped after just four months.
The Wednesday voice vote — two commissioners voted no — came despite a defiant 2018 budget address last week by Board President Toni Preckwinkle, who maintained the $200 million a year she expected the pop tax to raise was needed to avoid 11 percent across-the-board cuts. She warned of reductions in critical public health and criminal justice programs.
The tax was one cent per ounce of pop - enough that people started shopping outside of Cook County and the projected $200 million revenue was actually a fraction of that. Besides, people do not like being "nudged" and the soda pop tax was a perfect example of a socal nudge trying to get people to consume less.