They are paying for them. That is how the WTBTS works, the congregation is told what it costs and must raise that amount of money, then that goes towards the World Wide Work and is earmarked so the branch knows what they ‘purchased’. If you cannot or do not raise the amount of money, then you don’t get the equipment. And that is true for everything, the projectors/TV, the audio equipment, chairs, lecterns and table on the stage, they all have a price tag, you want it, there is a price list. Even the publications had a price tag, despite the donation, internally they handle a price list which must come from donation, if you didn’t provide the money (I was in a poor black inner city congregation, donations to the WWW averaged $1000/month for 120 publishers), your literature counter would be frequently out of stock for things like bibles, while you could go to another congregation and find they got boxes with the stuff every month.
Again, I have seen the accounting, I was doing it and this was part of my awakening, the previous brother that did the job had also left “for apostasy” and so was my assistant recently reinstated after he had been running accounts before that (I assume he came back for his family). If you ever want to wake up honest hearted people, make them do accounts at the Kingdom Hall, RBC or Conventions - the last one was what gave me the most evidence, I personally oversaw the second day after lunch counting money session (this was still 3 day conventions) and we counted over $10,000, a quick deduction is that you collected more than $15-20k at that point. Day 3 they told us we had collected $8000 and were short, the CO then sent a ‘bill’ to the congregation for the expenses through the elders.