When I used to live in Senegal, Dakar airport introduced "security screening" after baggage collection. Everyone had to put their suitcases and handluggage through a huge scanning machine. Ostensibly, that was also "for your security, Sir", in fact it was a tidy little earner for the customs agents who sat there ready to confiscate anything which they liked the look of on the xray machine (namely the electronics goods that a lot of Senegalese were bringing back for their families).
Also at about the same time, a number of arrivals at CDG were accompanied by passport spotchecks at the door of the plane on disembarking. Don't know if this is only done on flights originating in Africa, but I certainly have never experienced it off any other flight arriving in CDG. It considerably slows down the disembarking, I can tell you, as they are extremely fastidious in their inspection of every single passport.
My suspicion on this is that the process has more to do with stopping illegal immigration than any security measure, but who knows?