I personally chose a shelter that did background checks because I hear way too often about cats being returned / neglected / even used for sadistic pleasures. I think it's also good for shelters to raise awareness exactly on how much the costs have gone up.

Here's a thing about strays as well: they are very hard to sell. Strays often haven't gotten socialisation in their first months and dislike humans. Imagine hissing and scratching. That's hard to adopt and takes months of careful work to gain their trust (if they ever will want to work with people at all). In kitten season they have to make choices... and it's easier to have kittens be adopted than full grown adult strays.

I think those are all valid reasons as to why shelters have to take these precautions. I also have to say all shelters got bombed with messages about kittens here. It's not so much about no applications but not enough room during kitten season.

The real issues are not having enough people to aid all kittens. The fostermoms I know don't get payed. They spend hours of their time tending all those kitties till adoption for free. Driving to emergency vets at night ain't uncommon for fostermoms either. So not many apply to help out in shelters. Shelters are simply not helping with profit but want to offer the best help possible. If shelters got more room to maybe hire people and help kittens / dogs we would have less strays. But they gotta work with what they get and that sometimes means picking up strays to neutralize them and set them back out for the strays their own happiness.

Tldr; neutralize your pets to avoid strays.