They don't plan to shop at DTD though, or at least that is not their initial intention. Their initial intention is to park there to avoid having to pay for parking. What their plan is is to park at DTD, take a bus to the park they plan visit that day, leave the park via bus back to DTD so they can drive off park to get food, return to DTD to park, take the bus back to the park for the afternoon then take the bus back to DTD so they drive off park to get dinner before returning to DTD to get a bus back to the park for the evening.