I think that is less about rigor and more about transfer equivalency of credits. For example, suppose you wanted to transfer to Rice from a community college. You took your Social Science Gen Ed via an online Anthropology 101 class so you could travel for Spring baseball. It was a great class; you learned a lot and earned an "A." You also took chemistry lab as a freshman in case you wanted to do engineering and earned an "A"; you are now a business major but your chemistry class fulfills your Lab Science Gen Ed. All is well.
You graduate from community college with an A.S. in Business Administration after two years and enroll at Rice, where the coach loves you, with the intent of earning your B.S. in Business while playing two more years of great baseball.
Rice's transfer page states:
Note: The BioSciences, Business, Chemistry, Economics, English, History, and Physics departments conduct a thorough review of course material to consider granting Rice equivalent course credit to coursework completed at community colleges or two-year institutions. Chemistry requires that courses are taken at a 4-year college or university that offers a degree in Chemistry certified by the American Chemical Society. Additionally, Anthropology, Civil Engineering, ClassicalStudies, Economics, English, History, Philosophy, Physics, and Sociology may not grant Rice equivalent credit for coursework completed online.
So even though you earned an "A" in Anthro 101, Rice denies the transfer. Chemistry lab? No go. You have to RETAKE chemistry at Rice. Now you are playing great baseball but academically you are no longer a Junior but a Sophomore. Your graduation is delayed by a semester. You pay Rice another $$ for a fifth semester.
This transfer problem happens all the time. Unless you are transferring from a public community college to a public state system university, you are NOT going to have a seamless transfer of credit--particularly if you are in STEM or moving from JuCo to a private university. Even if the math course is EXACTLY the same, the transfer of credit system may not be fair to the student.