There is no evidence at all that Claudia Lawrence is dead, has been murdered or abducted yet everyone believes this to be the case - why is that? Let's not forget she unlike Madeleine could have gone off to start a new life but no one is suggesting that is what happened. Why not?
When an adult disappears in suspicious circumstances investigators have to look carefully at their background, lifestyle and those around them. Claudia Lawrence's disappearance was out of character leading police and family to believe she was abducted and killed.
Kate Prout's disappearance was also out of character despite the claims of her husband Adrian who insisted she had gone off by herself. Some simple checks revealed that many of her personal effects had been left behind, her bank account was untouched etc..
As you have pointed out Madeleine McCann was a child so unlikely to have gone off to start a new life on her own and nobody except SY has even mentioned such a preposterous scenario. It was Mark Rowley who made this comment in his recent interview, the fact that he should even have made such a stupid remark undermined the entire communication.