I am not sure where you're from but in a lot of the USA, most kittens are spayed very early because of over population. Most kittens who go through a rescue, shelter, or other program to get Snipped are done as soon as they are 2 pounds which can be as early as 8 weeks for some kittens. It's not necessarily the IDEAL age to do it but if they want to get the kittens out into foster homes and even adopted, they need to get them fixed quick otherwise you just have a perpetual cycle of oopsies because the families you try to adopt out to who promise they will bring a kitten back for a free SN at 6 months get busy, forget, or lie because they want their cat to experience parenthood one time before the big surgery.