Well said. I had coverage in all areas that I was in, except in the desert to the sw of Walvis. I've had worse connections in Pretoria...Maybe you missed that the 2G coverage is the light grey? 3G/4G are the blue colours.
I drove from Windhoek to Ondangwa and across to Rundu without having any signal issues on MTC.
Its very similar to the cell networks here, you dont get 3G/LTE out in the sticks but you do get coverage.
And I am talking about data.