I don’t think you understand the problem down there. It wasn’t polygamy, it was forced marriages to children.
Actually my reply you referenced was indeed to a question about polygamy. ;)
But to answer your query, one of the problems that the State has is the changing of age requirement to be married.
in 2005 I understand that the age to marry was 14. Without certain factions in the legislature wanting to GET these people the age would probably STILL be 14. So now the State/CPS has to go through this calculation not only about how old they child was, and when she became pregnant, but what was the status of the law at the time the pregnancy occurred. There is indeed the clause that the mate must not be over 3 years older than the girl, but that sounds to me like a technicality and if the state has to depend on that to build their case, then they have a REAL problem.
Younger than 14? You bet! charge em, indict em, convict em and throw away the key!
But according to the law, not people's wants, wishes, desires and opinions which is a LOT of what I see on FR anymore. People's opinions masquerading as facts and evidence.