"Resort course" is synonymous with fast-track certification ... nobody wants to spend any more of their limited vacation time than they have to in class. "Fast" is the appeal of such courses. I've spent remedial time with several graduates of those classes ...(Grateful Diver)
The term "Resort Course" is used by many different people to describe a number of different levels of training.
Some people would be referring to the Intro or Discover Dive class, which is a brief lecture, Confined Water session #1 of the OW course and is usually followed with at least one shallow open water dive (which may be considered Open Water dive #1). On a two week stay you could do as many shallow dives with that instructor/shop as schedule/finances allow.
Some people would be referring to the PADI Scuba Diver cert course, which is considered half way through the Open Water Diver course. Complete the first three chapters in the Open Water manual, the Knowledge Reviews following those chapters, take the Quizzes for those chapters, complete the Confined Water sessions #2 & #3 and then complete Open Water dive #2 (plus 3 dive flexible skills). The Scuba Diver cert let's you make shallow Pro guided dives "without" doing the Intro class each time you vacation. It also holds your place in the Open Water course, so you just need to finish the last two chapters of the book, Quiz #4 and Final Exam, CW sessions #4 & #5 and Open Water dives #3 & #4.
Some people would be referring to full certification in as little as 2 or 3 days at a resort. To do it in 2 days, the student would have to plan ahead, completing the academics on their own either by reading the Manual and completing the KR's before arrival at the resort, or by doing the same online with e-learning. Then there would be review of the KR's, 4 quizzes, Final Exam, All CW sessions and the 4 OW training dives. Even with all homework completed, that's a lot to do in 2 days and the vast majority of prospective divers would not enjoy or be well served by such a fast pace. There are a few who will do fine with the 2 day cert, IF the instructor/shop is capable and the student is properly motivated. 3 days is easier and common, even with non-resort dive shops and agencies other than PADI.
As stated above, some vacationers take more than 3 days to finish a resort course, even as much as 2 weeks, but the amount of time with the instructor is not necessarily increased, just a more relaxed pace.
With today's budget and time constraints, a very high percentage of the annual certified divers probably did the 3 day course, even though it may not have been at a resort. Depending on the instructor and the effort/ability of the student, some of those new divers do not need remedial instruction, although most OW divers will benefit from continuing their dive training.
Edit/addition; when using the 2 and 3 day class terms, I am not counting the time the student spends on homework. In my opinion the average student takes ~8 hours to do the academics, not including the KR review, Quizzes and Final Exam.