When did it become acceptable to give a toddler soda?

I can home from work to find my babysitter giving my toddler coke in her sippy cup. I was so appalled i completely lost my voice as I grab her cup and took her to bathroom and washed her mouth out. My sitter just sat there with a puzzled look on her face. I would never give my baby soda especially near the end of the day!! I felt bad because I fired her on the stop and I know she needed the money, but I can't get over the fact a grown woman would think that is acceptable to give a developing child soda.