First off, the last Sputnik was launched 1958. To my knowledge, neither Google and particularly not Bing own satellites (AFAIK Google bought a sat operator at a point but sold it again in 2007 or something ). Even if they did so they could just say “hey, let’s collect fresh images from this year” you would be rather disappointed by the resolution at pattern altitude. They may use satellite imagery for some things or zoom levels, everything else, particularly the crispy stuff in some areas is aerial photography and that all is bought in from corresponding companies doing this business. The pure acquisition of these images is a complicated process already, and the supply chain is pretty long.
Imagine how complicated and expensive it is to cover even a small country in a consistent quality for once, how flights have to be coordinated, how the weather can refuse to play along nicely for long periods making it impossible to shoot quality imagery covering large amounts of the ground with the same light and weather etc. - hence the patchwork with varying quality, colors, seasons, shadows, and cloud artifacts reflecting pretty much how much the planes of the supplier could cover on a flight. Then this material has to be processed accordingly and if you followed the general development of e.g. the Google maps imagery you will know how many years it took before some areas were covered in a sufficient quality without artifacts and a zoom level <16 (<2m/pixel).
In short, I think it’s just not feasible to acquire and publish fresh “satellite” imagery every year, and coverage, availability and quality highly depends on how much the imagery can be monetarized, which restricts the chance of getting high quality and current images from certain countries. Flight Simulator sales will certainly not make Bing spend billions to close the gap to Google’s imagery.