Look at this photo.
I am in the correct lane of traffic, naturally. There is supposed to be another lane of oncoming traffic. On the left you will note a white Toyota pick-up truck who decided he did not want to wait for traffic. He has decided to go "off road" and use the "sidewalk." If you look to the right of the pick-up truck (in the middle of the photo), you will notice a blue sedan. That lovely vehicle has also decided to not wait for traffic and it is attempting to merge into my lane of traffic. So a two lane has now become a three lane. But wait! There's more!
Ta-da! The other lane of traffic is no longer blocked and is attempting to flow. But it is now officially blocked by the white Toyota pick-up truck and now a Jeep. Neither vehicle was willing to lose their precious ground so they parked. Now our sneaky little blue sedan has merged into our lane leaving an "opening" between the Toyota truck who is on the "sidewalk" and our lane of traffic. A motorcycle proved that a vehicle could drive through and is making headway. So the oncoming flow of traffic is now attempting to also squeeze in between that little "opening."
Meanwhile, there is a road on the right. There is no stop sign, it is simply an "Every Man For Himself" rule when it comes to side roads. In your view, there is a large white bus who decided to not hesitate and force himself into my lane of traffic. There was no merging involved. It is pretty much like a game of chicken. He who hesitates is he who loses the game. The bus won.
Now you have had a small taste of traffic in Kinshasa.