Do they put someone in a coffin if they are going to be cremated?
Only if the family is stupid enough to pay for one.
As far as I know, there is a requirement for a cardboard container, which has a nominal cost and a coffin sans metal fixtures can be purchased, for a price.
Bottom line is: morticians and funeral home owners/directors absolutely screw over the living, playing on the grief of the family, making them feel cheap and guilty if they don't spring for the most expensive services available.
I suppose that includes a coffin to be cremated in and embalming prior to cremation.
It's all about the dollar, donchya know?
And the US funeral directors/owners and morticians are the greediest.