Apparently (according to Bajo_Cero2) this is correct...and a good reason not to go to migraciones t pay the overstay fee in advance.
OK, that explains why you have been making the visa runs instead of overstaying.
Do you know when this happened, how many overstays your friend had, and if the ban went into effect upon leaving or trying to reenter the country?
According to Bajo_Cero2, territorial borders not accessed by boat or plane are better.
PS: I believe all borders are terrestrial, whether accessed on foot or by car, bus, train, boat, or plane.