why don't cash back sites just use coupon codes?

sites like topcashback claim to pass all commissions they make to their users. why don't they just give us a coupon code that saves us the same amount of money? If they did this people wouldn't have to wait weeks for their funds to clear right?

submitted by /u/spacetimetrip
[link] [comments]

source https://www.reddit.com/r/beermoney/comments/1hphyym/why_dont_cash_back_sites_just_use_coupon_codes/