It occurs to me that well before the days of "follow the green line", one had to make position reports, then as radar coverage improved, they were omitted, but one still knew where the FIR/UIR boundaries were.
These days, I dread to think how many of us are actually aware of where the boundaries (ie the name of the waypoints) are and therefore when to expect a change of frequency/control.
CFPs/OFPs don't help much either - depends on the provider. Perhaps this is a contributory factor to this sort of incident.
mcdhu