I just googled "more churches per capita", and you'd be amazed at the cities who claim that. But...it doesn't mean variety
They really don't cover their business interests. They're proud and wide-open. One group (in the Bear River area just north of Ogden) uses the women as telemarketers and the men run the farm.
The Kingstons own restaurant supplies, payday loan stores, and other businesses - with an estimated net worth of about $150 million. In their case, the men work, the women do not (but the women are children are all on "welfare").
The established groups don't recruit, especially men. They have too many men already. (Think about it.) Part of their belief is "purity", and they don't want their lineage spoiled. The Kingstons believe their lineage was given directly from God, so they are particularly intermarried. The Colorado City/Hildale (Warren Jeffs) group is pretty much the same, with so many intermarriages that birth defects and common and disgusting (one "baby" was described as "a tomato").
What usually happens when a person goes "fundamental" is they start their own group, fresh, with their own angle on fundamentalism. It's not illegal (because they're just all living together without true marriage) unless child sexual abuse is involved.