Comment by WorldMaker

Some of the prevalence of gift cards in corporate culture is loopholes and silliness in tax codes and anti-bribery laws. Giving any cash to an employee counts as bonus income and needs tax withholding. Giving gift cards under certain values to an employee is a gift to the employee that doesn't count as income (and, worse, in some cases can be expense reported for a tax advantage as a cost of doing business, especially gift cards to restaurants where it may be assumed it is for a "business meal").

In a different direction, giving cash to a partner/vendor/competitor is pretty obvious to many laws as a bribe. Giving gift cards more resembles gifting swag or paying for a meal and is sometimes considered "allowed". Different companies have different views on that loophole, but some companies do take advantage of it. Enough companies at least did at one point that the "CEO is in a high-powered meeting and needs gift cards immediately" came from somewhere and it was probably that, wining and dining partners/vendors/competitors in "legally distinct from but quite resembling bribes".