[Kadin]

There's really no technical reason why imagery like that couldn't be contributed, and IIRC Google does use municipally-owned imagery in its products. A single city might not be a big enough source for them to bother, I don't know, but I know particularly in Europe I have seen copyright notices for national and regional governments when looking at imagery.

Though there are a lot of sources for satellite imagery right now; Google may not be that hard-up for new stuff. I suspect the commercial vendors they work with probably image the entire CONUS area every 12 months or so.

The imagery that would seem to be more in-demand would be the aerial photos used at very high zoom levels. I'm not a geospatial expert but I think these images are combined with some sort of LIDAR or multi-spectrum imagery to have height maps in tandem with the visuals. That strikes me as pretty expensive to obtain.