And why would you think that ? ......
Because I've coached and managed teams where the behaviour of referees is vastly different in friendlies
Because I've watched local games at various levels where the behaviour of referees is vastly different in friendlies
Because I've been to FL / PL friendlies (or pre-season tournaments) and the referees are far more lenient when it comes to certain offences, especially the breaking up of a promising attach
Because I've watched International friendlies where the referees are ALWAYS more lenient than in competitive games.
And I'll openly admit that I am more lenient in friendlies, even it is to some degree subconscious. I've sent players off for DOGSO and SFP in these games, but equally I know I have let players off with a quiet word for tactical fouls that I'd be reaching for a card for in competitive games. And I suspect if they ask themselves honestly that also applies to 90%+ of all referees.