Why Are Northern Highways Better Than Southern Ones?

DISCLAIMER: This topic refers to the route from Warri to Kano Only please.

I travelled recently from Warri to Kano and here are my observation about the HighWays:-
Southern Part
From Warri passing through Benin by pass, Ekpoma, Auchi, Okpella and Okene straight to Lokoja
POTHOLES: About 60% of the Road is filled with potholes, very dangerous I must say.
DOUBLE LANE: Less than 35% of the Road is double laned, Not good Either.
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Northern Part
From Lokoja passing through Abuja, Niger, Kaduna and Zaria straight to Kano.
POTHOLES: Less than 20% of the Road is filled with Potholes, at least this is good.
DOUBLE LANE: Up to 90% of the Road is double laned, a laudable feat