You can drop off any time after 6:30am and pick-up any time before 6pm. Not really a window as such. I've always assumed the number is just a deterrent - I've been late by a couple of minutes in the past and never noticed a fine. Though that might've been at the discretion of staff (e.g., to penalise lazy, repeat offenders rather than isolated case of traffic due to an accident).
So it's not only extortionate, but also arbitrary? Which favors people who are able to talk themselves out of any situation? Great (not for me though)...
