Cookies are not mandatory...however, depending on the GS Council you're in the cookies you sell/or take (in our case we pre-order and each family says "xx" number of boxes) you are responsible for. Read the permission slip, make sure to ask lots of questions. Cookies are an individual sale...unless you're at a booth (which will help her get to know her fellow troop members).
In our area we have girls from all over our school district in our troop. It's fun for them to make new friends...I have 14 girls and out of the six elementary schools we have four covered. We sing "make new friends but keep the old, one is silver and the other gold"...
We actually just had a girl sign up for the first time two weeks ago...she's from the next town over. Our girls took her in and made her feel at home and welcome. If that is not being done I would say look for a new troop.
Good luck...
ETA: Start your own troop as well. I never thought I would be any good at it or have the time. Now I am so involved with not just our troop but with our service unit. Best decision my daughter ever made "Yep, mom will do it"...is what she replied when asked "would you like your mom to be your troop leader?"
ETA x 2: We just finished our cookie sale for the year...I work in an office that only has four other people, my husband works from home...we sold 250 boxes of cookies...door to door, cookie booths, taking cookies with us anywhere we went. I aslo had one family sell 20 boxes. I told my parents..."the more we sell the less out of pocket you will have to pay". I also said "I hope you sell and even if you sell only two boxes I will be happy!"...
ETA: Just wanted to say that as a troop leader after meeting I cannot go around and talk to each parent and let them know how their child did. This is a volunteer position...yes they are going to have to correct the children....it's not all fun and games. I am constantly reminding my second graders to stay on task, to share, to smile, to have fun, we don't play with the toys that belong to the church. At the Daisy/Brownie age...the leaders still need to keep the girls on track. Are you sure the kids didn't say goodbye? Cause we don't say goodbye individually...we do it as a troop just before pick up.
Ask her what the money earnings are going to provide? They may be wanting to go on a lot of activities, THinking Day (can be expensive), Camporees can be expensive. I would ask for a parent handbook.