Maybe because they happen so frequently in the States Mom's look straight at the parents as the guilty party, they know the MO, the old story 'my baby disappeared from the crib' just does not wash with them. And if you notice the child always comes first where as with the McCanns they ONLY ever thought of their own selfish needs and their supporters also follow suit, otherwise they would be asking them to return for a reconstruction and prove their innocence as any normal parent would.
http://www.justicequest.net/forums/showthread.php?t=63385
http://www.justicequest.net/forums/showthread.php?t=63385