Right, that's often how they do it, but you seemed to be saying that this was something that should always be done. Maybe I misunderstood.

As for how countries actually do it, there are a lot of borders out there where you can legally cross without telling anybody, like the borders in the Schengen area (possibly excluding France at the moment, not sure what's going on with that) or the border between the UK and Ireland. Certainly, tracking is the norm, but it's not universal.