I think that’s because at MCO, many SW passengers will be using DME and have tagged their luggage so it never reaches the luggage carousel. Since bags fly free, there’s no disincentive to check your bags. When we fly from MCO to MDW, the number of people waiting for luggage is about twice the number we see for the MDW to MCO flight and it takes forever to get our bags. We are usually using DME as well, but last trip, we flew in a day early (to avoid some incoming weather in Chicago) and spent the night at a hotel near the airport so we had to retrieve our own bags. It was the quickest we have ever gotten luggage after arrival.