and yet children have been doing this for decades...even after 911, and there hasn’t been a single episode of lemonade stand poisoning.. boy are you paranoid...
I had a lemonade stand on the golf course in our suburban back yard elsewhere as a kid - made a little money too, and I hope that whatever kid is now living in that house is doing it too. But the potential for anybody getting poisoned by a terrorist or just a bad batch of juice is ridiculously miniscule there, - it's a totally different ball game with the kid who's set their stand up up in Central Park selling to forty customers an hour.
For the sake of argument, let's set the precedent & have wall to wall unpermitted food & drink stands in Central Park then, with no health controls at all (& because the law has to be enforced equally, that's exactly what you'll get if you do set that precedent for one person).
The logical consequences of what you're suggesting are pretty damn scary there, not to mention a pain in the neck for pedestrians in the park who like to see their public parks remain parks & not everybody else's kids' front yard lemonade stand. A dense urban situation, not to mention a public park, poses many more complications & consequences than your average lemonade stand on a suburban street or backyard golf course does.