You need aerial imagery from different angles.

Thats surprisingly hard to buy from imagery providers, because most of them only want to point their cameras directly downwards.

They fly their own planes these days.

https://blog.google/topics/inside-google/google-earths-incre...

Too bad it's a video. Fast forward about 2 minutes.

Or: https://youtu.be/suo_aUTUpps?t=121

Fly plane. Zig zag. 5 cameras, then photogrammetry. StreetView, from planes.

Not really effective for non-urban areas.

Lenses don't work that way, surely. Any image taken directly downwards will include angled elements offset at a greater angle away from the centre line. Also, how hard is it to add an extra camera or two if you're already flying over, sure double/triple the data but that must be relatively easy to handle once you have the infrastructure for image handling and such.

Do we know how Google obtains this data ?

Could drones be used here ? It looks like it would be a good way to refresh this data often on the cheap.

(drone is the loosest sense, a balloon would do the trick)

A couple of public blog posts made it obvious that Google flies planes.

Or with lighting from different angles - different time of day.

Aeroplanes and satellites take successive overlapping tiles of the same area as they move. This gives data from multiple angles.