Most of this is normal behavior. I just went through Google Maps in a totally different part of the country and it blurred the names of businesses and things like that. Cars on the other side of the road especially disappear. The only thing I wasn't getting was different copyright dates, but I didn't look very long, so that's really the only part of this that I find questionable. They could possibly use a previous version of the photo if there is some sort of obstruction (such as a bus). I'm not sure.