Red card in a friendly: yes or no?

Last weekend I watched a friendly match and the referee didn’t give a card. In my opinion he could give at least one direct red card.

Should players not be booked for an offence because it’s a friendly? Should referees change their match policy in non-official matches? Do you see it more often that the man in black doesn’t show a red card in a such matches? Let me know what you think. Red or yellow card in a friendly: yes or no? (and why)