Absofrigginlutely it's about the $$$. And you're spot-on there by not saying it's ALL about it for the $$$, though an implication might be argued.
I've got no bone to pick with anyone who rehearses regularly without compensation; Often there's a genuine need due to experience level (and I'm not saying that's the case with you personally), and sometimes both pay scale and gig importance make it a given, no matter how experienced and comfortable the musicians are.
All I'm saying is I've been doing this and getting paid for it for over 45 years. I'm reasonably good at it, I show up on time, I'm prepared and I keep my mouth shut and do my job on regular band, sideman, sub & pickup gigs.
If you need me to start attending regular band rehearsals when I could be making more effective use of my time woodshedding for other paying gigs or attending said other paying gigs, your gigs need to be at a high enough pay scale to justify it. Either that or you need to pay me for rehearsal time (like many churches do in these parts). Otherwise, with all due respect, I'm not going to be a good fit for your band.
Peace