I own the main dual tower PA ( subs n tops ) the rhyth git owns the mixer. We both provide monitors. His desk is old and worth very little compared to my Yam Stagepas pair, but it works just fine.
Neither of us ask the other members for any kind of " hire " money. Of course if we had no PA then the whole band would have to split the cost
of hiring a PA. If we only put vocals throught the PA, then it's the singers problem to buy or hire a vocal only setup, but in our crew, bass drum, bass git, rhyth git , keys and 4 vocals all go through, so its every bodies PA, except me and the mixer owner ask nothing for providing it.
On the other hand, if either his mixer or my tower Yamahas go down and need repair, i would expect them all to help with repair costs.
If i left the band, my towers go with me.