It is possible that these look this way because of the relative rarity of incident data geocoded in these area which means that the boundary is "fuzzy" when generated from the data. As I noted above, the detail level is very accurate where there's busy freeways, and can be off by a few miles when it isn't.
In particular, where incident data is very rare, the boundary is shown as the midpoint between incidents investigated by different offices.
The areas of no color occur where there's very little incident data, and what data there is was in conflict (e.g., there might be a small patch where two or more offices generated incidents the overlap back and forth such that it isn't clear whose area it is)... this causes small islands of other offices within the dataset, and when those islands were small I deleted them manually, leaving a color-less area.
The little peninsulas are formed for a similar reason, when there's multiple incidents that reach out beyond a natural boundary from one office, and then another office clearly covers all around that. Sometimes that's due to where roads are connected in mountainous areas.
Good point... what other areas of the state are also federal-only? Vandenberg AFB might be an example?
I'm not an expert on the military. I think most military bases that have more than a few acres and are in the hundreds of acres, which are closed to the public are areas of exclusive federal jurisdiction. Vandenburg and Camp Pendleton come to mind as exclusive jurisdictions. Others I can think of would include Edwards (USAF), 29 Palms (USMC), China Lake (USN), and Lemore (USN). I'm not sure for the smaller facilities like the Los Angeles Air Force Base, which is pretty small. Even then I would think it would have an exclusive jurisdiction since it is closed to the public. Small facilities such as the Navy's language school in Monterey are not closed to the public and probably concurrent or maybe proprietary jurisdictions where the federal government is a property owner only and don't usurp any local authority. This is all from conversations with NPS and USFS employees when we lived in California. Hubby, being a civil engineer for a county had to know this stuff as well as there were Bureau of Reclamation reservoirs, national forest land, state parks and NPS boundaries he dealt with.
My late husband was trying to find a list of national parks and their jurisdiction type. The older, larger parks are exclusive jurisdictions and those that are not are usually a concurrent jurisdiction where the state and county have jurisdiction within the park and the NPS has full jurisdiction as well. According to a friends we had in California, who worked for the NPS, most of the time the NPS provides all services in concurrent parks as they think they have responsibility for drawing so many visitors into an area so they will take care of the workload as opposed to creating a burden on local agencies. Surprisingly Grand Canyon National Park is an example of this as it is concurrent, but I've never seen any AZ DPS or Coconino County Sheriff's deputies in that park. I don't think Lassen Volcanic, Pt. Reyes, Joshua Tree, Mojave and others are exclusive. My late Hubby talked to some rangers at Death Valley who said that park is concurrent. He was working on finding a list when he got sick so it never got done.
Rest assured that the area offices south of Lake Tahoe are on the crest, there isn't any fuzziness there. The only exception is the road to Devils Postpile National Monument, which is accessed by vehicle from Mono County only so it is in the Bridgeport Area Office. The Sierra Crest is not easy to access for any of the offices in the central and south Sierra Nevada, at the ends of their jurisdiction so the chances of a Sonora Area Office officer to respond to an accident east of Sonora Pass are very low. I seem to remember that in the cases of callers not knowing where they are, if a westside unit finds the wreck/etc. east of the crest they wait for a unit from the respective area office to arrive and take care of the investigation. Somewhere in my Hubby's notebooks are some maps of some Sierra Nevada area office jurisdictions which show the crest as the boundaries. I picked up a pretty tough respiratory infection during Christmas and am down at my younger brother's house in Phoenix and the books are in Payson at my parent's house so I can't scan and post them right now.