as the church that stated that people are free to marry whomever they chose, with certain restrictions (ie couldn't be previously married, free consent, etc.).
Don't be foolish. Polygamy was banned fairly recently, consent wasn't actually required of the woman who was considered chattel, and even age restrictions are civil not religious. There is nothing in the bible about how old a person, especially a woman, must be to wed.
Why is it illegal? Because the church forbade it
Why did the church forbid it? Because earlier religions forbade it. Why did they forbid it? Because inbreeding resulted in deformed offspring and being ignorant as they were, they attributed it as punishment from the god(s) du jour.
So why can tenants rerent their units to tourists at a higher rent than what they pay their landlords? Actually, they can’t. These tenants are violating a multitude of San Francisco ordinances, starting with rent control itself, which affords their own low rent protections. If the “host” tenant is renting out their room or unit at a daily rate that exceeds their own daily rental value, that tenant is violating the San Francisco Rent Ordinance, which states that a tenant cannot charge more rent to a subtenant than what the tenant is paying their landlord.
Moreover, by offering their entire unit or room as a short-term rental (defined as a rental for less than 30 days), the tenant is also violating the San Francisco “Apartment Unit Conversion Ordinance.” That particular ordinance prohibits the rental of residential units to tourists or short-term transients without obtaining a special permit first. Violations of this ordinance has penalties, including fines of not more than $1,000 or by imprisonment in the county jail for a period of not more than six months, or by both.
Depending on the neighborhood zoning designation, it is also likely the tenant is breaking zoning laws, which require that hotels in residentially zoned districts obtain a conditional use permit. It is also probable that your tenant or his “guests” are afoul of tax laws because, in 2012, the San Francisco City Treasurer office stated that short-term rentals were subject to the city’s transient occupancy tax (also known as the “hotel tax”). Lastly, assuming the tenant has signed an SFAA lease, they are in breach of the “no subletting” clause of their lease agreement. The most recent version of the SFAA lease is even more explicit, and specifically states in the section entitled “Use” that “No hotel use, such as daily rentals, shall be made.”
Does that clear things up?
Someday somebody has got to decide whether the typewriter is the machine, or the person who operates it.