Your instinct is often correct, especially for modern stamps.
For many modern stamps, used prices are higher than mint prices. A lot of the stamps see very little postal use. Many postal services release sets of stamps when only some of the issued stamps are supplied to post offices. The sets, often, have a face value that makes it 'economic' to print stamps. With the decline in mail due to digital communication, philatelic sales have become an important source of income. More sets are printed in smaller quantities but at higer combined face value. It should be noted that higher prices for 'used' stamps often only apply to genuine postally used specimens.
It is not always required the cancel is scarce for the used stamp to be worth more than the mint counterpart. The 1922 Irish overprints on British stamps have a number of examples. Quite a few sets are worth more used than unused hinged sets. In most cases mint never hinged are the most expensive still. However, among the high values is a set that is priced higher used than mint. Some individual values are as well. The two Harrison overprint sets for use in vending machines and the one with the 'long 1 in 1922' variety all are priced highest used. The reason is the comparative rarity of the used stamps.
The 'Saorstát Éireann 1922' high values were overprinted with adjoining narrow and wide settings by the stamping branch of the IRS at Somerset House in London. Pairs with this composite setting are very expensive. Unmounted mint, the three horizontal pairs are priced at € 4,200 by Hibernian. Hinged unused are priced € 2,400. Used are not even priced but just quoted as 'rare.' The postal use of high values is rare. The postal use of pairs of high values is extremely rare.