Light from Late Comers phones with e-Tickets

How are folks handling Late comers when it comes to E-Tickets.

My FOH staff commented.

"The question has come up again about how other theaters who scan tickets on mobile phones deal with latecomers.  As in, when the latecomers enter the theater, do they have to show their lit phone to ushers in order to be seated?  If so, how distracting have the lit phones been for them?  Or do they print out/ write out a location pass on paper for latecomers to hand to the ushers for seating?"