You right, but I still see this map as a catalogue of found meteors, rather than an informative visualisation. To make your observations clear, you need to normalise this heatmap by the population density.
It depends on what you're after. What you're suggesting would would also distort the data, but in a different way -- it'd make it look like Antarctica was far more likely to get hit than it actually is.
One would expect the true distribution to be extremely uniform, right?
However, there could be a favoured plane of arrival, like the solar system plane, and with a circular cross section of the Earth I'd expect less debris/area near the poles.
(I don't know this, I'm just extrapolating from what I actually know.)
> ... with a circular cross section of the Earth I'd expect less debris/area near the poles.
As it turns out, Antarctica is a very productive place to look for meteorites, first because there isn't really a preferred geographical zone for meteorite impacts, and second because of the large, empty ice fields, against which newly fallen meteorites stand out.
One of the most famous meteorite finds of all time, ALH84001, was located by simply driving across the Antarctica landscape and watching for dark objects.
One would expect the true distribution to be extremely uniform, right?