People in IV often walk in the street since few streets have sidewalks and some of the few sidewalks are too narrow and inconsistent to support comfortably walking by yourself or with friends. This is especially true for friends walking between houses and parties in the evenings, who may be in a large group and somewhat intoxicated. Often the larger the group in the street, the more intoxicated on average the members are. Drivers have to be careful in IV - people will walk in the street in front of you.
There are a lot of people riding skateboards and bikes in the street as well as walking. Most often the people walking in the street will not be inebriated, but as the sun goes down or the weekend approaches, the probability of finding intoxicated pedestrians increases.
Navigating a car quickly through the streets can be hampered by pedestrians seemingly oblivious that they could be run over. Normally the density of pedestrians is fairly mild but there are several periods of higher density. The population of students will pulse onto the streets from campus as classes end at the end of every hour or half hour and peak toward the end of the day.
During specific holidays the density of pedestrians will spike or crash depending. Halloween has one of the highest numbers of people on the street, most concentrated on Del Playa, and radiating out from there. It is often very difficult to walk against the crowd on Del Playa, and there is a danger of being trampled during Halloween. Winter break and the holidays associated along with summer break and 4th of July offer some of the least number of people in town, let alone on the street.
Even with some streets having sidewalks, people seem to prefer to walk in the street, and it is ingrained in local culture. The idea of pedestrians having the right of way has been pushed to the limit of driver and bicyclist patience, but after living here for a short while you will end up not worrying about getting anywhere particularly fast and just drive a bit more carefully and patiently.
From August 2014: "Construction began last Monday as a part of the Isla Vista Pedestrian Plan, a Santa Barbara County project announced by Third District Supervisor Doreen Farr that plans to improve pedestrian walkways in I.V. The construction is a part of a four-phase sidewalk project that will renovate and install new sidewalks from the 6500 block to the 6700 block of Del Playa Drive, with construction slated to be completed in three to five weeks."
From January 2015: "Last week, Isla Vista Foot Patrol announced a policy stating all cars in Isla Vista that are parked on or blocking a sidewalk, even in front of residents’ driveways, will be cited for traffic violations starting Feb. 15."