The Troop leader of that GS troop should be reported. What you are saying is absolutely unacceptable behavior.
We did a "cookie booth" in front of the local supermarket this past Saturday, and those girls knew better than to do anything like you describe. Our girls did ask the question, but never stepped in front of a cart, nor did they get more than a foot away from the table.
I'm serious, my friend, if you can remember the Troop number, call the Council and report it (if you can't ask the store manager, he/she will have the information because someone from the council made the arrangements)
I will have to ask the store manager, I suppose. I don't remember seeing a troop number, or any uniforms either.
It's been a long time since I was a scout, but I seem to remember having to wear my Girl Scout uniform whenever I was out representing the Girl Scouts. When I was trying to sell cookies, for instance...