The LA Times explores further:
As short-term rental websites such as Airbnb explode in popularity in Southern California, a growing number of homeowners and landlords are caving to the economics. A study released Wednesday from Los Angeles Alliance for a New Economy, a labor-backed advocacy group, estimates that more than 7,000 houses and apartments have been taken off the rental market in metro Los Angeles for use as short-term rentals. In parts of tourist-friendly neighborhoods such as Venice and Hollywood, Airbnb listings account for 4% or more of all housing units, according to a Times analysis of data from Airbnb's website.A search for Encinitas on Airbnb shows hundreds of units currently available. The prime-location apartments and condos envisioned by the failed Measure T would have been even more likely to end up as vacation rentals.
Perhaps Encinitas' Housing Element Task Force should consider a prohibition on vacation rentals in any new developments that take advantage of upzoning?