Childhood Obesity and bad parenting

I'm at a "storytime" event with my infant at the public library, and lo and behold there's a kid acting out, screaming, defying his mom, etc.  He was older than the age group for the class, but that's a moot point.  The mom looking for some way to pacify her child, could have left the room, but no, she shoves about 24 ounces of apple juice down his throat to shut him up.  That's right, 360 calories and 72 grams of sugar.   I'm thinking to myself, good idea, reward the kid with a sweet sugary drink every time he acts out.  Heck, I'd throw a tantrum for that.   As much as I wanted to say something, it wasn't the time or place.  But it got me wondering....how many parents out there are either so lazy or have so little control over their kids that they're resorting to shoving sweets down their kids' throughts to keep them quiet.  An occasional miniscule sucker after a traumatic day at the doctor's office?  Fine.  But just because your kid is acting out as a result of you being a bad parent?  NO.