Not aimed at you in particular, but I don’t understand why voucher codes are used in this way. In the sense of the “rules” of retail, using codes to offer a blanket discount on a product or range of products, should really only be used if you are not allowed to advertise a discounted price to the RRP (a grey area of RPM).
Voucher codes for discounts first became popular about 10-15 years ago, the idea was to give select people the codes, which were typically timed, to offer loyalty and encourage a purchase within a given timeframe. Then, people like me started to use them as a way to get around RPM, which was rift in the bike trade back then. And to a lesser degree still is.
If though you are not tied to an RRP and the discount is available to everyone, it’s better to just change the listing with a “was” and “now” price, opposed to making people have to do something to get the discount.
It’s weird: It used to be we only used vouchers for general discounts because we had to. But now, it seems they are the preferred way to apply a blanket discount, with the result you are putting a barrier up to a sale and for the vast majority “hiding” the discounted price from them, so potentially losing lots of impulse sales.
I do a bit of retail consulting from time to time and often see something similar when a shop has a rail of clothes advertised at “half marked Price”. The people in the shop think this is great: They know that rail is half marked price and assume everyone looking at it does too. But they forget the simple fact that 90% of people don’t read signs (or popups), they just look at the price, and if it says £20, it’s £20, even though with the sale on, it’s actually only a tenner.
I always tell them: Take down the sign, cross out the old price on each item and stick on a new tag with the cheaper price. 9/10 though I get back “but that will take too long”. And they then wonder why they can’t shift the sale rail.
As I say, not aimed at you Mr. Webdeer, almost all the devs do it this way. It’s just a really odd way to do things and almost certainly is losing you sales.