> One thing I never saw in Germany: cops hiding behind trees, hoping to catch people who were speeding. Traffic cops are very common in the USA, but basically unknown in Germany, since the major highways don't have speed limits.

You won't see them much on the motorway, since for most of it there isn't a speed limit, but radar controls in towns and rural areas are somewhat common.

> Another thing I noticed in Germany, where there is a speed limit, people drive that limit, and not 5 kilometers above the speed limit. The drivers make the assumption that the government must have had some good reason for imposing a speed limit.

You'll literally only ever see that when A) the driver is some old person driving carefully, or B) the area is common for radar controls, or has radar traps installed. The unwritten rule is to drive 10km/hour faster, according to the speedometer, than the speed limit allows, which works out to ~5km/hour over the limit, due to the way speedometers are calibrated.