Comment by chias
3 days ago
Not sure this is the reason but: it is generally not easy to get a satellite over the poles. You launch close to the equator in the direction of Earth's spin to take advantage of the (very substantial!) speed you already have due to the rotation of the planet. Getting from an equatorial orbit to a polar one requires a huge amount of fuel / energy. You can't just sort of "drive it over".
Source: played a bunch of Kerbal space program
There’s enough satellites in Sun-synchronous orbit (97-ish degree inclination) that polar coverage should be pretty good by now, I’d imagine. The gap from the big guns (GEO and MEO) is more than made up by LEO.