The fact that the Council of Elrond was held outside at noon and had no security leads me to consider a number of possibilities: 

– Rivendell is entirely empty of other elves

– No one in Rivendell cares about whatever Elrond is up to

– Rivendell has internet or television, hence why no one leaves their house

– Elves hate the oudoors (explains Nargothrond, Menegroth, and the Woodland Realm)