Airbnb has become politically controversial in high-priced, regulation-obsessed cities like Los Angeles and New York. Hotels and hotel unions quite understandably see Airbnb as competition in the short-term lodging industry, and wish to regulate it intensively (if not to destroy it). One common anti-Airbnb argument** is that Airbnb, by making short-term lodging more affordable, actually reduces the supply of traditional apartments—that is, apartments leased for a month or more at a time). The argument runs as follows: units that are on Airbnb for a few days at a time would, in the absence of Airbnb, be rented out as traditional apartments. Thus, Airbnb reduces the housing supply and raises rents.

This argument rests on an essentially unprovable claim: that Airbnb units would otherwise be rented out as traditional apartments. More importantly, the argument proves too much. If Airbnb hosts reduce the supply of apartments by not using their houses and spare rooms as traditional apartments, why isn't this equally true of hotels who are not using their rooms as apartments, or homeowners who are not renting out every spare room? And if homeowners and hotels are reducing the rental housing supply, why shoudn’t they be forced to rent out their units as traditional apartments?

Finally, the argument rests on the assumption that Airbnb includes a significant share of the rental housing market. For example, LAANE (a union-affiliated policy organization based in Los Angeles) recently issued a report claiming that Airbnb takes ,7316 units off the Los Angeles rental market, which “is equivalent to seven years of affordable housing construction inLos Angeles." But since Los Angeles produces very little "affordable housing" (whatever that term means) this statistic proves nothing.