It has almost zero to do with the equipment put into low orbit. The atmosphere still blurs the image as much looking towards the earth as it does looking away from the earth. Spy technology isn't using adaptive optical systems (at least none as powerful as the astronomers are), which gives them a limit of (being GENEROUS) of 0.1 arcsecond resolution.
At an altitude of 100 miles (the absolutely lowest for stable orbit...your spy satellites would be closer to 200-300 miles), that 0.1 arcsecond resolution is about 0.00005 miles...
pr 1/4 of a foot. That means, the satellite imaging can just define two dark points that are 3 inches across on a white background. Anything smaller than 3 inches becomes a single dark point.
If the satellite is 200 miles high, then it becomes 6 inches (it's linear).
So, for something to even be able to SEE the distinct letters of the headline of your newspaper (let's say 1 inch each), then it needs to either be in an unstable orbit, or at 100 miles, and resolve better than 0.035 arcseconds. to actually READ the headline, it would need to be at least an order of magnitude better than that.
Realistic resolution for a classical digital imager on a satellite at 150 miles (say, imaging video or scans over several hours)?
1 arcsecond average resolution (atmospheric average) would give 3.8 foot resolution.