I don’t believe the mccann’s were letting their kids go off to pa3d0s but I don’t buy the abduction story either, I think the most likely scenario is that the kids (all of them including the other family’s children) were all sedated/drugged so that the adults could enjoy their holiday without the kids annoying them, but Madeleine was drugged less than the others, awoke, and had a fatal accident within the room in an attempt to find her parents. Covered up because there would be a hell of a lot resting on it if it ever came out (the decent careers, the money, the friendships, the custody of the other kids, all being charged with neglect). I think that could be an explanation as to why Gerry especially seemed so capable of going off to play tennis days after her disappearance. His background as a consultant already gave him a distance towards death etc and I think perhaps it was rationalised as ‘not their fault’ because it was an accidental death.
There are bits of the story that just don’t add up to me and the above isn’t exactly a sound theory either but it’s the closest I can think of to a conclusion. If the cadaver dogs detected cadaver and madeleine’s dna in the hire car - hired after her disappearance - maybe this was transferred into the car by the mccann’s after they had cleared up after the accident, I could be wrong but I think it’s quite hard for dna/cadaver to be completely removed from a place but easily transferred.
That’s my little bit of armchair tattle police work anyway