ALL the Orlando Parks' pricing shows how many days they think the average customer wants to "do" the park.
Disney's 2nd, 3rd, & 4th day costs about as much as the first day and then the price drops for Day 5 and then really drops beyond day 7. This suggests that Disney thinks you'll naturally "do" about 4 days, and that they're more motivated to keep you for Day 5 , 6 and 7 (see https://disneyworld.disney.go.com/admis ... eme-parks/
They want a monopoly on airport transfers and to get it they'd much rather put you on the bus (Disney's Magical Express should come back soon).
SeaWorld, at the other extreme is more like: Pay for Day 1 and get Day 2 for free. They are self-aware enough to know that they're so unlikely to get you back for Day 2 that they're willing to give it to you for Free.
In between is Universal, which is more like a 2-day place. They are going to work real hard to "take" it from the "back half" of your week at Disney.
Disney "wins" days 1 2 3 4 Universal wins days 6 7. And there's a fiercely-fought battle around Day 5.
The point is: if they think you've taken a 5 to 7 days vacation, they are strongly motivated to keep you on-property every night you're in Florida, and also know there's a real "danger" that you'll leave to "do" Universal or Sea World if it was as easy as hopping on a train.
I suspect they even have data on how Disneyland Paris' TGV is a mixed blessing--on the plus side, making it easy for car-lite European households to *get* to Disneyland Paris, but also making it easy for them to be whisked away--back home (day trip only) or to split time with Paris itself.