That's an INCREDIBLY populated and heavily traveled area, and still has a decent traffic flow even at night.
Sometimes it's a little iffier at night as there's some gang issues in parts of Mira Mesa, but definitely not nearly as much so where she was last seen.
There are a ton (ton is an understatement) of pretty similar looking buildings in the complex she was apparently staying in, so if she wandered out that would definitely possibly be confusing, especially if she has the start of Alzheimers/dementia, but it's also a very populated area and I can't imagine it'd be long before someone stumbled on her and could help her get back to the right unit if she were lost among the complex there.
The shopping centers on the other 3 major corners (basically) basically nearby at Westview and Mira Mesa Blvd are also very busy - especially as the holiday weekend kicks off with deals, etc.
The least busy would be the one most 'across' the street from her that has Daiso, HMart, In N Out, Applebees, Shell, etc. but on weekends, especially, it's also still very busy. Though that center has a much higher non-native English first language speaking population than the shopping centers on the other corners given the anchor stores are targeted at the (mostly) higher Asian population in much of Mira Mesa (nearly 50% there)
I'm very surprised she's still missing at this point given how populated that area is and how heavily traveled it is.
It'd be quite a distance for her to go (and likely too far given her age, etc.) to get to an area that it'd be hard to find her (the preserve or Lake Miramar would be the closest, really, but not knowing where they were and the distance would make those highly, highly unlikely IMO - and too heavily used by locals, especially on weekends, for those to be plausible places) relatively easily.
And although I wasn't listening to the scanner frequencies when she was first reported missing, our SDPD ABLE copter pilots are absolutely amazing and are virtually always called out very quickly on missing person cases. I've actually been up with them, including just across the freeway from this location when they were searching for others missing here locally, and they've been out there looking even days later when they weren't on time sensitive calls, so I'm confident they'd have been FLIRing the area well.
Given that, I imagine they've been over the area extensively with FLIR, making me suspect the most likely thing might be her probably curled up somewhere in one of the buildings (some are still under construction there) and just in a lesser used area.
Local media's been doing a decent job trying to get it out there, which will hopefully help.
Praying she's found soon!