My BK friend at one centre says outside people do paid room cleaning.
Are you saying they pay contractors to clean? That would help with having a clear calculation of costs needed to be reimbursed by the hirers.
If the cost of cleaning and other goods and services is less than the charges, there is a profit left over.
It is difficult to ascertain exactly what all the costs are so that hirers are only charged at a "not-for-profit" rate, especially when much BK volunteer labour is not paid for, and how do they calculate other prices e.g. electricity etc.
For the BKs to maintain "not-for-profit" integrity in such a situation, they’d have to err on the side of loss - and that loss has to be carried by someone - and it is. It's partly carried by the people who donate their time, energy and skills for no financial reimbursement. That time, energy and talent can - and should - be given a proper dollar value.
My experience is that people who have and give money - easily quantifiable - are considered as donors in a different way to those who give their time and energy.
"Services in kind" i.e. "in lieu of payment" is tangible tax office stuff. Each year, in countries where BKs have charity status, they give receipts for money donated and people can use it as a tax deduction.
Volunteers, who’re often foregoing other income, should be able to get receipts for "services in kind" to the value of $xxx.
The BKs should allocate a realistic value on people’s time and energy commensurate with what they’d pay ”outside people” to do that task, note that amount as a donation in their bookkeeping and issue a tax receipt to the donor.
For example, if a kitchen hand usually gets paid $20 / hour in that country, then a volunteer BK kitchen hand should be noted as having donated $20 for every hour they've worked. If that kitchen hand then later fixes the electrical wiring, that should be valued and accounted for at the standard rate for electricians.
The BKs would then see which side their bread is really buttered. It would be a big surprise. The spiritual "serfdom" paradigm could be totally replaced, with the sincere 24/7 sevadaris being properly, quantifiably appreciated, while the (merely) fiscal donors have less influence to ”buy” favour and preferential treatment.