Is it typical for parking lots to change their rates hourly?

Many downtown lots sit on private property, and their owners can charge whatever they please, whenever they please. The exceptions are the Green P lots, run by the city-owned Toronto Parking Authority (which raked in more than $40 million in revenues in 2005). But the TPA’s mandate isn’t to skim cash off motorists; it’s to make sure that affordable short-term parking spaces are available. Green P rates are adjusted twice a year according to supply and demand and aren’t hiked other_wise. Except, that is, the lot by the Air Canada Centre. On game nights, the price goes from $6 to $25. Apparently nobody’s above sticking it to Leafs fans.