There are similarities but in Madeleine McCann case, I believe it was an abductor. McCanns' subsequent odd behaviour and discrepancies in their stories and those of Tapas group (friends they were spending holiday with) are a result of trying to minimize their negligence and because they felt guilty. All of them were leaving their small children alone in their apartments every single evening for hours. They claimed they did frequent checks, while in reality they were not frequent nor thorough. And McCanns' apartment had patio door they were leaving unlocked, and children's bedroom was facing public street. From the patio you could also reach street as it was a corner apartment. So basically they 'delivered' that poor girl to the abductor. It would be easy for anyone to do it - just wait till they leave the apartment, sneak into it through the unlocked door, take a sleeping child and stroll back to the street. You don't have to make great leaps to imagine how it could have played out. But as in JB case, the fact that they were respected members of society (although not as rich) with connections in right places, helped them to avoid consequences of their behaviour. I'm sure if it happened to some working class family, social service and court would be after them in a matter of days.
