回复：they didn't collect my wife's

I'm not sure.

But the basic function of I -94 departure record card is that when a foreigner leaves this country the I-94 is supposed to be given to INS at the departure airport so that INS has a record when you leave.

And when one comes to this country a I -94 card should be filled out.

That is what my understanding according to the content on the back of the card.

Wish everything is good to you.