Keys on shabbat is doable without an eruv¹²³. (It's not considered carrying if it's an integral part of your clothing.) Eruvs are more for strollers/carrying small kids, dessert/wine when invited for lunch, etc.
Yeah, this is covered in the Eruv wikipedia article as well, but was not mentioned in the L.A. Times article (at least as far as I can remember—it’s been 15+ years since I read it).