Why do shelters use clay litter?

I don't think cats have any problem adjusting to another type of litter (maybe the pellets a little because of the different texture). And yes, shelters don't have a lot of money to be buying expensive kitty litters. But they do take donations and people could donate good kitty litter.

yes it is the cost, plus the is in the most abundance

Our shelter uses the clay litter in the cages. There is nothing worse than having a kitten who climbs the cage bars, falls in his water bowl and then gets in the litter box. So the clay is better as it will not stick as much to the wet kitten.

Now in our big play pen area where we have up to 8 cats, we use the scoopable. And so far we have never had one problem with cats going from the clay in the cages to the scoopable in the play pen.

Shelters are on a limited budget and have to use what they can get, but another reason they use the clay is that with kittens you are not supposed to use the scoopable kind, also with nursing moms. The clay is more dusty which can lead to air quality issues, but it's more convenient and the only one that is universally acceptable to use for most cats.

Shelters are run on a limited income. They buy the cheapest litter possible. Most shelters are always in need of cat litter. It is expensive and they go thru a lot of it.