Actually, the average SEAS student is unlikely to be any stronger academically than her peers in the other undergraduate schools. Academic ability is probably pretty evenly distributed across the undergraduate population. Just as an example, you can compare the SAT scores of the overall incoming class at Penn to that of the class entering just the school of engineering. At the time of my writing this post, the links below show data for the class of 2019:
Overall Stats: – Engineering Specific Stats
CR: 690 - 780 – Engineering CR: 640 -750
Math: 710-800 – Engineering Math: 680 - 780
Writing: 700 - 790 – Engineering Writing: 650 - 750
http://www.admissions.upenn.edu/apply/whatpennlooksfor/incoming-class-profile
https://www.seas.upenn.edu/prospective-students/undergrad/
As you can see, Engineering students tend to have lower standardized test scores across the three sections. Of course, the SATs are only one indicator of academic ability but I think this speaks to the overall reality that Penn students across its undergraduate schools are pretty evenly intelligent and differ only in their areas of academic interest – and each person is valued for whatever their contribution might be!
Also I don’t know that it’s harder to get into Wharton than Engineering-- i think both attract very specific students who are all extremely well qualified and competing for a limited number of places among other very qualified applicants. And once in the schools, you really don’t see a lot of transferring so it is unlikely that it is harder to stay in Engineering for an engineer or easier to stay in Wharton for a whartonite-- they’ve each attracted students well suited to the type of work they’re doing and for students with those interests and abilities sharing a classroom with other students who are equally interested and able is probably equally difficult.