I imagine it does depend on the area. We just moved here las summer, has trouble getting the post office to aknowledge us, because they didn't want to believe that a person could renovate a cowshed and live in it. The actual lady that delivers our mail is great, but she did mention that the commune was "moving forward", and that all the boxes were being changed, and bunched together at the ends of roads, at intersections and so on, and that nobody had any control over keeping their mailbox outside their gate anymore. The idea being that the postie delivers all houses on the road without even getting out of her car, in one go.
Down in the post office itself, they asked for proof of address in the beginning... and them being the link in the chain in us getting any proof of address, that was impossible. They asked "what house is it, who lived there before", and eventually said "but you can't live in a shed", and went on to "but you'd never get planning permission for that"...... Well, we do live here, and we DID get planning permission. That's up to the mayor, thanks V muchly, and not the busybody in the post office. Lol.
I fail to see why these people go out of their way to make life hard for people. Surely dealing with undeliverable post is even harder than just bundling it off on the person with the name on the envelope.
As for John, above, I'd say the post office have either left it on the box, and it's been nicked, or a "do gooder" either a neighbour or some old dot cotton that works at the post office has decided to take it into their hands of confidence, lol.
It might be worth asking La Poste, though, before reverting to vandalism.