Originally Posted by
LoganFlyer
It's so that if you book this as an award ticket, DL can "justify" charging you hundreds of dollars in addition to the miles by claiming it's a fee they charge on every ticket instead of the base fare. To be fair, DL is far from alone in this shady practice.
They are only somewhat tangentially related. There's no award surcharges on awards ex-US (either one-way or roundtrip). YR surcharges are charged regardless of origin. YR surcharges also differs from the amount charged on award tickets.