It's worse than it seems.
First, the congregation takes out a loan...from the Watchtower Bible & Tract Society. Even if a lower interest rate can be financed through some other banking institution, the congregation must pay for its new Kingdom Hall by borrowing money from the WBTS. Part of the loan agreement is that the WTBS becomes the sole owner of the property. THEN the property is developed by volunteer labor from the local brothers who will use the Kingdom Hall.
All of this so that, a few years down the road, the WTBS can profit TWICE from the local members - first, from the interest on the loan and second, from the sale of the property. Sometimes the sale is because the WTBS instructs those same members that they need a new Kingdom Hall and the process begins all over again.