Growing up LDS I heard a lot of stereotypes about funerals. About how LDS funerals were very happy because supposedly LDS people felt so secure in their knowledge of the Resurrection. By contrast all the other religions had super sad funerals because their belief in the Resurrection was defective in some way. I even once heard it suggested that it was common in other religions that people were in such despair that they became overly dramatic and upset because of this failing.
Growing up it was hard for me to accept these stereotypes as real, because the first funeral I ever attended was a Salvation Army Church funeral where the tragic despair and sadness I had been taught to expect simply wasn't there. As a little kid I was confused. I had been told that funerals were sad and that non LDS funerals were sadder. The people I was seeing were smiling, happy to see each other. It felt like a family reunion. As the years have passed it seems the happiest funeral I can remember.
By contrast the first two LDS funerals I ever attended were for people who died young in tragic circumstances. While I have no doubt as to the faith and belief of the people in these situations, I also observed that they were intensely sad. Who wouldn't be? I have attended funerals conducted in at least four, maybe as many as five different religious traditions. Specifically coming to mind I have been to Salvation Army funeral's with traditional hymns sung along to a brass band, an informal Catholic funeral held with the eulogy structured around the rosary meditations of the mysteries of light, LDS services, a non religious service focused around people coming together and sharing memories of the deceased, and an Episcopalian funeral mass. Each funeral service is unique, and how happy or sad people are in response is very individual. Generally each has its own mix of steadfast faith and hope mixed with the very real tragic sense of loss. Generally I have seen much to honor and little to criticize about most of the funerals I have attended. It is unfortunate that a lack of interfaith contact allows myths about non LDS funerals to be perpetuated. If Jesus can weep at the tomb of Lazarus then it is perfectly acceptable
for family to be sad at a funeral. People who are sad are in need of
comfort, not judgements about how much their believe in the Resurrection
or not. No matter what someone believes about the after life, their loved one for now is gone. While of course there is nothing wrong with being attached to your own cultural traditions surrounding funerals, if you find yourself making assumptions about other people, maybe try attending a funeral from another tradition. From what I have experienced, I expect that if you do it with your eyes open and an open heart, you will come away touched by what you see and feeling more charitable towards people who are different than you.