The Emporium Can't Count

In the category of “Evidence that businesses are run by people - stupid people”, look closely at the following, a loyalty card from the Emporium (a bar in Hartlepool):

[The card says “Get this card stamped every time you buy a pint and get your 16th one FREE!”; above this are two rows of seven boxes each; the first row is numbered 1 to 8; the second row is numbered 9 to 15... “6” is notably absent.]

This has probably never been an issue, since the card is valid up to 7pm.