There is an electric bill, water bill, let's say the parking lot has to be resurfaced every 5 years, seats need recovering every 3 years, the carpeting replaced every 10 years, toilet seats replaced every 5 years. All those costs can be broken down and averaged out, and divided by 50 weeks. Then they can estimate how much $ it costs to operate and maintain the building for each assembly.
They CAN but they DON'T. That's really the point here. They pick a number that experience tells them will more than cover the expenses so that the surplus can be sent to the Watchtower Society.
Did anyone check out the link earlier in the thread about the Surrey Assembly Hall in the UK? They regularly take in WAY more than they need. In the real world that's called PROFIT, which is something religions shouldn't be earning. And A$$embly Halls throughout the western world do the $ame thing 50 week$ out of the year.
I wish the USA had such a charity commission keeping track of how religions screw their people here.