Tulane’s model, like most schools in the 25-50 range, is still primarily non-binding EA plus merit aid. They have been test driving ED for the past couple years, but ED at Tulane would logically function a bit differently than it would at the big ED schools.
Duke, Penn, Vandy, NW, etc. typically do not have much merit money as part of their formula. At these 10-25 schools, binding ED is the bread and butter part of their yield/admissions model. Typically filling half of their total seats through binding ED. Which is a great way for those schools to fill up a lot of seats with kids who would tend strongly to be full payors and who have average to slightly above average stats. And also a way to greatly increase their yield statistics as compared to the schools above them (HYPS), whose brands are soooo strong that they can eschew binding ED for non-binding SCEA but still post ultra high yields.
My guess is that Tulane has started to test drive ED as a way to lessen its historically heavy reliance on merit aid. But for now, Tulane probably fills a much smaller number of its seats via binding ED than the big ED schools upstream from them. My guess is that Tulane’s ED is the way to enroll more full payors who are eminently well-qualified but who have slightly below average stats (and who therefore wouldn’t be getting merit money anyway). Tulane’s ED probably shores up the stats at the 25th percentile at low aid cost, and also help the yield numbers. Tulane’s EA/merit money shores up the numbers at the 75th percentile, but with a significant merit aid cost.
It would also make sense for Tulane (which is as sophisticated on this stuff as any school I’m familiar with) to defer the super-admissible kids (who will go elsewhere and kill Tulane’s yield) unless/until they have some indication that such kid is a realistic enrollment candidate for Tulane. A campus visit might be one indication. A Tulane connection with a family member might be another indication. Applying for the bigger Tulane scholarships (PTA, DHS) would be another (since those require extra effort and also signal that the family is looking hard for merit money).
Bottom line, it is a market and each school uses its own recipe to ENROLL (not admit) a class that meets their institutional goals and budgets. All pretty logical once you view it from the school’s perspective.