[fragmede]

> Why overprice something by ~50% and add a voucher for the same amount off

Preying on human psychology and the non-rational consumer. People are emotional impulsive creatures, and the marketing department knows this. If you think you're winning in some secret way only available to you (you're so special!), for a limited time only (so don't miss out!), it taps into something primal that turns off the rational part of our brains, and suddenly we're buying something we don't need at a price higher than we'd ideally pay.