I started as a Brownie in 1966, the age range then was 7-10, 10- 14 for Guides the Rangers. The same as it is now, except now there are Rainbows 5-7.
Guiding is absolutely not about teaching girls to be good little housewives. We do do cooking yes, but it's just one thing. I do not see my role as a guider as that of a cookery teacher teaching how to make things "from scratch" every time. Guides are now very much "girl led" in that the girls have a big say in the activities they do.
On this occasion it sounds like the aim was to do something for Valentine's day, decorating cakes and a sweet treat sound fine to me.
At our hall, which is pretty standard in terms of equipment, we have a kitchen about 3.5m square, not much worktop, one sink and an old, small cooker. There is no cooking equipment at all, not one bowl, set of scales, wooden spoon or oven tray. Absolutely everything has to come from home.
We normally plan meetings so only one group is cooking at a time, the logistics of processing 10 bun trays of cupcakes through an oven which only takes 2 trays at a time in an hour and a half makes it almost impossible. A cake mix would be the only way to go with the whole group, God knows how they got them all mixed, cooked, cooled and decorated during one meeting. Hats off to your Dd' s leaders!
Oh, and if the only cooking you have done is with your own DC at home, you can have no idea of the absolute mayhem of 25 kids with added sloppy cake mix. Or how far said cake mix can go......