An admin fee is a % of the order that is added at the admins discression. It is transparently charged, as it is visible in the members carts.
This fee goes to the admin of the group as a payment for undertaking the work of organising the group and the order, liasing with Honest to Goodness, collecting and making payments and organising the distribution or colleciton of the order by members.
Depending on the size of the group and the complexitity of the order, there can be a substantial amount of work that goes into being a group Admin. It is up to the admin if they choose to charge a fee and how much that fee is.
How do admins collect this fee?
The fee is charged to members as a % of their order. This amount is paid to the admin, along with the rest of the payment for the order. The admin then makes the payment to Honest to Goodness minus the admin fee. Many admins affectively use this payment to pay for their proportion of the order.
eg. members are charged 5% admin fee
member 1: products & shipping total $200.
cart total $210
member 2: products & shipping total $300
cart total: $315
Admin collects $520
Admin pays Honest to Goodness: $500
Admin keeps $20 fee as payment