Same here. A sub for a freebie is not the best solution.
But if you have three guys who are committed and get rewarded from a freebie, that's there thing and they enjoy it. Maybe the sense of pride and the fun and hang are enough.
Fourth guy can't be bothered. One of these things is not like the others.
They should replace him with a more like-minded individual. And there are some pretty good musicians out there who will play freebies, especially when you do some quick math and realize that as a weekend warrior, you're not getting paid nearly enough to offset the hours of rehearsal, performance, travel, equipment, etc. That $50.00-$100.00 average gig pay amounts to pennies per hour at best.