As for pitty vs staffy... I used to work for one of the notorious councils as an animal control officer... here in qld ^_^
Now... the reason they do a blood test is simple... actual pitbulls are rare and 'pitbull type' animals were being taken. They were taken on the basis that people were breeding new strains from other breeds to fight in pits. Creating new australian pitbulls from staffy, mastiff and other lines.
Some people with some money got together and faught this and now DNA is required which has completely thrown out eliminating the new pit rings. And all because of the general incompetence of one person
If you know the story behind it all you will know who that one person is
I put in objections... and got fired. Anyone interested in the story, I will be happy to PM about it ^_^
As far as identifying them for sure... it is easy. Staffy and pitty are easy to tell apart. Purebred amstaff and pitty may be more difficult as they are essentially the same breed. Even crosses of certain breeds bred to look like pittys are generally easy to spot. Though some people have merely bred purebred staffys... papered... to take the place of pits.
My concern would have rather been eliminating dogs that clearly had been in fights or bred for fighting instead of going on the ridiculous rampage that the notorious council went on... taking peoples pet dogs from them for no reason other than one persons personal vendetta.
Man I have some stories from that place... I almost got involved in the court case that stopped the pet dog killing because they resembled a pitbull a little.
Ok... ima stop ranting now ^_^