Sorry, but I think you're very wrong in that assumption.
I don't think I know of a small rescue that isn't strapped for cash, and virtually everyone works as a volunteer often even the principle, and they often "sub" the rescue with their own money.
Adoption fees are peanuts when you realise what it costs to look after the cats - basic vet checks & neutering swallow every penny of that and more, before you get to any treatment the cat needs for other conditions, sometimes special foods, looking after them while they recover enough from whatever state they were in when they were brought in.
Then you get all the costs of running the place - power, water, maintenance, council tax, washing, bedding, replacing equipment, collecting cats that need rescuing ...
The larger rescues (e.g. RSPCA) are often run very much like a business, but with all the branches they have with mostly volunteers working there again, they have to have very strict rules in place and sadly as with many big businesses "computer say no" is the rule and the people at the coal face aren't allowed to consider individual cases.
At some of the very small rescues, there's just the owner and a handful of volunteers so their policies are completely down to the owner. Some are very pragmatic - a decent but not 100% perfect in every way home is still better than a crowded cage - but some are so close to the animals that they sometimes lose track of that. And of course that owner has to sign off on every adoption.
Yes I completely agree that many rescues need to be more pragmatic when it comes to re-homing animals, but the one thing they aren't is any kind of money making venture!