The Watchtower corporation(s) in themselves don't generate an income like an individual does through employment. The corps hold assets such as property and investments. These assets can be converted into cash.
The corps protect the assets and cash. Without these the organization ceases to function.
Like any well managed corporation, the WT finds ways to reduce costs, maintain the strength of it's assets and look for new ways to increase funding.
All funding is given voluntarily to the corportation (branch) by members. The WT corporation has millions of members that give funds and personal assets to them every week as 'donations.'
So, the corporation (branch) benefits from the money received. Of course, the persons in control of the corps spend a lot of money but they never risk the long-term financial health of the Org.
No strings attached. No accountablility.
ginger