I think there's a psychological element to "claiming" your discount. I don't see many people coming to a conclusion of "They are going to make me click a link

I think there's a psychological element to "claiming" your discount. I don't see many people coming to a conclusion of "They are going to make me click a link in order to get my deserved discount? Give me a break." Also, if only %80 percent claim it, then you saved yourself around half a percent of lost revenue (20% of 3% discount)