Pedigrees do not require tests. Nor does the KC, as realistically you can get away with doing the bare minimum.
BUT the KC registration enables you to see when the tests were done - which is very important (and honestly I cannot state this enough) - and how often they have been done. Results for ailments, like PLA for example, can change over a period of time and errors can be made. KC registration is not just about being able to gloat about your dog being a pedigree but rather the assurances and peace of mind that come with it.
A dog that shows a score of 0 at 2 years old (when most Stud Dogs start) could show a score of 1 or even 2 by the age of 4 or 5. I know a bitch that had a score of 0 at the age of 2 then by age 4 her score was 2 (which means she should not be bred from - and the breeder instantly retired her and alerted the owners of pups from the previous litter). The last thing you want is to be using a stud dog or a bitch that's 4 or five years but not been tested for PLA in 2 or 3 years.
That is why designer doodle breeders are so dangerous, unethical and a downright disgrace to breeding - because they know all of this and they do not give one single, solitary, fuck. Why? Because the potential owners don't care and they know there are people out there who want a particular characteristic (that let's be honest half these dogs don't have) enough that they'll buy anything.
Find me a cockerpoo/maltipoo/shitpoo/goldendoodle from parents who have health tests as extensive as the dog below and I'll never mention dodgy designer doodle breeding again. KC Registration is how breeders can find exemplary dogs to use as stud dogs for their bitches and to ensure that unhealthy dogs (for lack of a better term), such as the one I mentioned above, are not bred from again.
Yes, some KC breeders are unethical and shit. But the KC website and the ability it gives you to properly search dogs for their health tests - going back generations (and you can use also Champ Dogs for this) is worth it's weight in gold. You are far more likely to find a dog that comes from healthy stock if you do your research and the best tool you have for doing that is going through the KC and checking the health tests extensively.
KC registration does mean nothing at the end of the day but the tests that come with that - that are verified and done year on year, are crucial when buying a pup.
You might find a cockerpoo breeder who has done tests for PRA in their Spaniel or their Poodle, but I guarantee you - I'd literally bet my bank balance - that they won't have done them before each litter the bitch has and they don't have made sure the stud dog has done the same. If people want to run that risk (alongside all the other awful things these breeders do) that's their call...personally, I couldn't sleep at night.
https://www.thekennelclub.org.uk/search/dog-profile/?dogId=8c069bd5-c77b-e911-a8ad-002248005544
Rant over. 😁