It has less visibility than those because there were no western nations (and hence western media) involved with boots on the ground. Or planes in the air, for that matter. The other thing is that the bulk of deaths were knock-on deaths from things like famine and disease rather than military violence.
However, it is still a good indication of just how little attention we pay to Africa here in the west, that people in general don't even know that it existed.
Also when British Empire and similar were in Africa stopping the wars and the like it was considered racist so now the done thing is to leave the Africans to it.
'stopping the wars' wasn't considered the racist part. 'taking all their stuff and not giving much back' was.
And for the Congo in particular, their experience under Belgian (well, Leopold II) rule was so horrific that other colonial powers exerted pressure on Leopold to give it up. The death toll in the Congo at that time was about the same as for the recent Second Congo War (plus the war's aftermath). Given the population of the day, it's estimated that the Belgian rule in the Congo halved the population, whereas the recent war 'only' claimed a bit less than 10%. The Belgian rule also left a lot of people maimed without hands, since there were bounties on hands, and the payors weren't too fussy about where they came from. Leopold II is one of history's lesser-known evil kingpins. After Leopold was forced to hand it over for management elsewhere, it became a more regular colonial story of exploitation for little in return.
In short, for Congo in particular, the modern day is better than it's experience in colonial times, even with the recent war.
However, it is still a good indication of just how little attention we pay to Africa here in the west, that people in general don't even know that it existed.