Amen to that!
One day we were just doing a hop from Port Harcourt NAF Base to DNPO, Port Harcourt International Airport, under IFR. It's not very far from one place to the other, so that we got a late hand-off from NAF Tower to DNPO Approach.
We were being vectored for a close-in final when something didn't feel right, even though there was nothing on TCAS, so that I asked about any other traffic. It turned out that, yes, there was a Fokker 27 on about a five-miles final, about where we were just positioning!
We did a go-around and then re-positioned behind the F-27 for a normal landing. Once we had parked I went over to speak to the captain on the F-27, who turned out to be a Filipino or an Indonesian or something like that. I told him that we had nearly had a collision there, depending, and that his transponder did not seem to be operating, since we had seen nothing on our TCAS.
That cued a sort of vague look around the F-27's cockpit, to locate the transponder control head looking rather dusty and unused. He explained that, no, they never used it, because there was "no radar" in Nigeria, as there was not.
I mentioned that ICAO had recommended squawking Mode C in any case, so that one might show up on TCAS, which he seemed to take as a not very interesting bit of aviation trivia. As another local crew had once told me, they did not have TCAS themselves, so that there probably did not seem to be much point in squawking.
Welcome to Africa!