Well, most of the ones who would hide out there are much better prepared to hunker down for multiple days. And would not have called 911 from their dying cell phone.

Based on the when they placed the 911 call (around 8:30 PM on Easter Sunday), they likely underestimated how soon they'd be back to their car when it got dark.
And they likely only had their phone, maybe a bottle of water and the clothes on their backs when set out, but we'll probably read more details in days ahead.

But they're not unusual: On our own little day hike down in Crystal Cove that same day, it was rare to encounter anyone with much more than a bottle of water (granted there are a lot of trail runners). As we pulled out from the parking lot in the early afternoon, a large (we assumed a church) group had just arrived to start their own hike.

Rescuers found both of them as of today, and they were both transported to area hospitals. News reports state they were separated. The guy was found without his shoes, extremely dehydrated and disoriented. He told a rescuer, when asked if he knew where he was, "Newport Beach". He was found about 1/2 mile from the parking lot. The woman has been found and airlifted out. Both were stuck in the dense chaparral when they were found.

Here's a topo map of the trail they were hiking along: http://www.mountainbikebill.com/images/Thumbnails/TrabucoHolyJim/HolyJimMap-LR.jpg

And a description of the colorfully named trail: http://www.greeneadventures.com/2011/02/07/holy-jim-falls-one-of-orange-countys-best-known-hikes/