The fact that a lot of people do it customarily doesn't preclude for it to me morally reprehensible.
To bring it to the extremes: If I found myself visiting Germany during World War 2, I would still strongly object to killing jews, even if it was "customary" there.
And since know this is a reductio-at-hitlerum, I will try again: I would not seek or consent or engage to having pedophilic sexual intercourse if I found myself in certain neighborhoods of Thailand, where apparently it is commonplace.
Perhaps a bit less extreme: I would not expect someone who is a convinced vegetarian to start consuming meat when they arrive to my country just because meat is consumed in almost every meal here.