https://en.wikipedia.org/wiki/Price_discrimination#Coupons
It's unclear whether banning price discrimination as a whole is a good thing. Is it really a bad thing that people with more money pay more, and people with more time can get a discount?
Yes, it is. It is blatantly unfair to charge different people different prices. You can illustrate this with a thought experiment: nobody would think it's ok if I charge Joe $5, but charge Bob $10 because I don't like him very much. Price discrimination is very much the same thing, just with the mechanism obfuscated and dressed up in pretty language so that it doesn't trip people's "this isn't right" detector as easily.
Are you sure? People often cheer on this kind of thing if they also think Bob's an asshole. (And there's no rule against it in most places unless you don't like Bob for fairly specific reasons)
This isn't as airtight proof of "unfair" as you think it is. Moreover this happens all the time without people being outraged. McDonalds might charge Joe $5, and Bob $10 for the same burger, because McDonalds likes Joe very much for using their app, so they send him offers.
Even if we do grant that charging people different prices is fundamentally "unfair", it leads to all sorts of strange conclusions. For instance if some retailer has some product on discount today only. Is that also "unfair"? I don't see how "buys a fridge on Wednesday rather than Thursday" is a morally justifiable reason to give different prices than say, being able to scout out a coupon or not. Should we ban time limited sales as well?
McDonalds gives people deals in their app because it tricks people into installing the app which they use to collect their customer's personal data (even when they aren't using the app) which they can sell or exploit in any way they see fit. It's a terrible deal for the customer, but they don't know any better because they don't get to see how that data is used against them.
Price discrimination leads to exploitation and enables bigotry. We've been being conditioned to accept it because ultimately companies want to abuse it to make more money at your expense. The only thing standing in their way is that most people understand that discriminatory pricing is unfair and dangerous https://link.springer.com/article/10.1057/s41272-019-00224-3
If McDonalds had to choose one price for an 8 piece nuggets, they would have to make a choice to either be ultra cheap, and anyone could happily afford those McDonalds nuggets like it was the 80s again, or they could choose to target up market, in which case they would compete with other expensive nuggets and some other business could take the market share for "extremely cheap nuggets"
Price discrimination distorts natural market forces that would otherwise drive competition, create opportunity, or "punish" hostile practices.
That's not all of what coupons are for.
They're also a form of advertising. If you give them out to an influencer in your niche who can bring you great customers, you can make a lot of extra profits.
Imagine you're making an app for managing hair dressing salons. If there's a particular Youtuber popular among hair dressing salon managers, you can do a deal with them where their viewers get 20% off on the first year of their subscription to your app, and the influencer gets an extra 3% of that revenue.
You do this because you expect that people watching that channel are already hair dressing salon managers, and hence are very likely to become big spenders with your company once they start using your services. It's a great deal for everyone.
Honey turns that on its head by indiscriminately offering that influencer's valuable voucher code to everyone, reglardless of whether they've seen any of their videos.
But not everyone is equally fortunate, and for some people the time investment to find the right coupon might be what makes them able to afford a necessity.
Then you miss the point of the coupon codes, they're for measuring ad effectiveness. The discount is the incentive for the customer to reveal to the business where they learned about the product and who was responsible for the sale.