Because it costs a lot of time and work to make satellite imagery look good even for a small area (and thats the advantage on ISDGs side ... they concentrate on a small area)! For extended areas (which SimHeaven does), you either have to pay unbelievable amounts of money to others who do this job for you (yes, there are aerial imagery providers who can do that for you - for lots of money), or you just take what is "freely" available. And Simheaven decided to go the free route (where even that rout is not 100% water tight when it comes to licensing rights!) by just plain sourcing Google Maps / Bing Maps data ... and thus his results can only be as good as the source data is (he applies some automatic color correction ... but that can only correct the absolutely worst things ... never fix inconsistency issues). And don't even think about him (yes, he is a one man show) correcting extended areas for us ... because he alone would not manage to do that in his entire lifetime (yes, our planet is big, and thus aerial imagery is very extensive too).