In the case of Canada the grass has 12 months to recover. Most permanent circuits run race meetings and/or track days nearly every weekend so unless they have come up with ultra quick growing grass that can go from seed sowing to fully formed roots systems (which grass run-off areas rely on to hold the underlying supporting material together) overnight, that idea does not really work for many of the classic F1 circuits.
If they did manage to develop a suitable fast growing grass strain, I guess a beneficial side effect might be that the grass would grow so quick it might repair itself between each car going off, though I am not sure Safety Car interventions every few laps for marshals to mow the run-off areas so that spectators could see the track would go down too well.
Edited by ExFlagMan, 12 September 2019 - 15:30.