I don't know if it is the case with the OP's relatives, but it is possible that one or more of the travellers do not have 100 percent freedom of mobilty. I had foot surgery a few years ago, and on my first trip afterwards, to MSP, I gained a new appreciation for what people with temporary or permanent mobility limitations go through
Parking in the underground Lincoln Center also means that the travellers can use the underground concourses, a nice thing if the weather is inclement. Also, at one time, a discount was offered if the parking stay was prepaid at the underground booth before the start of the performance (I'm not sure if that policy still exists).
[rant]
I find it disturbing that some FTers, whom I assume have full freedom of movement, somehow look down at those who are not as spry and mobile as they themselves are (a recent thread in the Europe forum concerning someone asking about driving between Prague and Berlin drew some mean-spirited responses). It might behoove those blessed with freedom from infirmities (for now) to consider the reasonable special needs of others before blasting someone who dares to want to use a means of transportation that would not be their own first choice. [/rant]