If you want to have pictures of your Disney World vacation, they’re going to include you in a mask.
If you spent the money for the PhotoPass service, you’re going to want every picture you can get.
It’s a simple thing, and to be sure, and it’s not going to convince everybody to keep their mask on, some people just won’t care, but every little thing is going to help.
And there will certainly be people for whom this is all the encouragement needed.