This is another legal loophole Watchtower has piggy backed off of.
This is the reason Bethelites are members of "The worldwide Order of Special Servants". They must take the "vow of poverty" in the same manner Catholic nuns and monks do which excuses the church from making employer national insurance contributions. However it is assumed that the church and the monastic community will care for the ministers in their old age, which has always been the case for mainstream churches. In other words those in regular cloistered communities will neither be a burden to the state NOR left to fend for themselves.
Watchtower has no such scruples, however!!!
They do not want to pay employer contributions yet screw every ounce of work out of the bethelites. Then, if they get old or sick or are surplus to requirements, they will be unceremoniously dumped with no unemployment benefit, health insurance or pension.
Disgusting, like the Federal, local, property and income tax laws they evade (501c 3)by pretending to be a religion that does good works, watchtower yet again sneaks by the government on the coat tails of the mainstream church.