San Francisco's law before 2014's so-called "Airbnb law" was black and white, what Airbnb was promoting was illegal. Administrative Code Section 41(a) used to forbid renting out residential units for "tourist or transient use", which is defined as rentals of less than 30 days. San Francisco made a surprising, and thorough, attempt to legalize but regulate short term rentals in 2014, the "Airbnb law". Here is a non-final version of the legislation that was passed to amend the law.Technically, it's not Airbnb that violated the law, they're just a listing service. It's the individual owner who rents out units that weren't legal to rent, and also owners that rent to businesses that allow it, and businesses to allow it. By promoting the rentals, setting rules, and handling the money, Airbnb could be seen as a participant in the acts, or allowing the acts, but it's not clear that this truly snags Airbnb. It also doesn't seem to apply to apartment renters who sub-rent.I don't see any loophole for Airbnb, HomeAway, VRBO, or anyone else. Perhaps they thought they had one, but Airbnb's website until recently promoted people to complain about the law rather than arguing that they didn't violate it. They were walking a tightrope, because they couldn't assure owners it's legal for fear of being wrong, yet they couldn't tell them it's illegal lest they admit to taking illegal lodging funds.There are strong reasons for these laws, not just the stated concern that tourist / executive lodging takes long-term residential housing off the market, increases rent prices, and undermines rent control laws. Real hotels are subject to myriad rules to protect customers and the neighbors - fire safety, security, inspections, disabled access, etc. They go through planning and get approved. They're accountable for ripping off customers and vice-versa.Another thing - even when a tourist rental doesn't violate the hotel law, it probably violates your rental agreement if you're a renter, your CC&Rs if you're a condo owner, and probably some zoning codes and other local rules.Unregulated rentals have a potential for abuse, and the legitimate businesses feel they're unjustly penalized for following the laws. Not everyone wants daily and weekly tourists roaming their building or neighborhood. Some of that is just due to an "not in my back yard" attitude, but they might have a point. Residential areas are quiet, with responsible neighbors and just enough parking. Short-term visitors cause noise, congestion, and wear and tear on neighborhood resources.Not every short term hotelier is a regular person just trying to swap apartments or make a few bucks - there are shady slumlords, developers, and others out there who make mint running illegal operations. You may recall one of the biggest, CitiApartments / Lembe, that caused tremendous harm to the San Francisco market for years with illegal evictions, unlicensed conversion of entire buildings to executive rentals, harassing and abusing tenants, distorting real estate prices, and eventually, bankruptcies and foreclosures that left a lot of people holding the bag.The new law is a little bit restrictive because it doesn't permit professional hosts. You have to: (a) be a permanent resident of a unit in order to rent it out, and you can't rent out the whole unit for more than 90 days (it's okay to rent out part for more than 90 days, if you are still living there), (b) carry $500K of insurance directly or through Airbnb, and (c) collect and pay the hotel tax. Beneficiaries of rent control cannot charge renters more than they are paying the landlord.