And here is where we have the constant inconsistency ~ I have had them ask me to provide my card and ID, even when showing my MB. I suppose with anything else it really depends on CM, supervisor and the wind. Disney is just really bad at consistent policies across the board. I'm not going to be without a card until they stop making them because most my experiences required a card.
NOTE: I stay offsite 90% of the time, and drive to parks. Next week I'll be there 5 days onsite but will still drive to the parks probably twice. I've had it handled all kinds of different ways including by holding up card/ID they wave me through.
There is no one correct answer.