"Bob G., am I missing something?"
James, not that I can see.
If you set aside any possible digital compass feature, a GPS receiver cannot tell which way it is facing or pointing if it is stationary. That is the primary reason why a few of the newer receivers have a digital compass added on. As soon as it starts moving in some consistent direction, it can tell the direction of progress. Where this gets messy is at very low speeds, because it can't tell what is intentional progress and what is simply position "noise" and sitting at one point. So, each manufacturer has built in proprietary fudge factors for these small details.
If a military GPS receiver is in a jet doing Mach 2, you need lots of these fancy fudge factors working together, and the sequential position fix rate is very high. At Mach 2, a tiny jiggle is a big error distance. In ordinary civilian receivers, the fix rate is much slower. In one particular model that I use, the fix rate appears to be about twice per second. That's still way overkill for what a backpacker needs for a maximum speed of about five or ten miles per hour. I've seen some receivers that have been modified to slow the fix rate down to about once per ten seconds, and the primary reason is to preserve battery life. To get the good out of that, they had to figure out exactly which functions could go to sleep and which functions had to stay awake full time.
The very simple receivers such as the old Geko display some position numbers well, but the "map" display is just about zero. The newest receivers have very complex mapping displayed, but they use lots more battery power to drive it.