Just learned something new

I was reading a post on another community and I just learned that it’s normal practice to not lower the coffin/casket until after the family have left ? Is that more common in certain states of the US ? What about in different countries could people chime in.

What is the reasoning ? I am so intrigued as in Australia we lower while everyone is there. In my 9 years doing this job we have never not lowered in front of everyone.

Thanks!