An online petition calling on San Francisco to overhaul laws that allow landlords to evict tenants for hosting on Airbnb has amassed more than 26,000 signatures, fueled by social media and a hand from the giant hospitality website. "People should be made aware that current law is allowing this to happen," said Peter K., a retired educator who started the petition a week ago. Peter asked to withhold his last name because he rents to Airbnb visitors in his San Francisco home and wants to avoid any trouble with city authorities until the law is clarified. The petition was motivated...