My husband and I had double insurance - Kaiser and Blue Cross/Blue Shield.
When he was fighting cancer, we’d go to Kaiser for the MRIs, blood tests, CT and ultrasound scans - and then take the results to the (far better) Blue Cross/Blue Shield doctors at Loma Linda, City of Hope and Disney Cancer Center for diagnosis, treatment and prognosis. We felt he got the best care that way - Kaiser, of course, was loath to give us the results of the tests and we had to fight them on this, but eventually prevailed. Usually we’d have to go in person and demand hard copies of the results b/c Kaiser would take six or more months to send over the results, if at all, then hand deliver them to the non-Kaiser doctors.
The doctors outside of Kaiser kept telling us to “get away from the Kaiser doctors” - but we used them for the scans b/c otherwise we’d be charged 20% of the cost by Blue Cross.
Exactly what others who have Kaiser have experienced. You need a secondary insurance to Kaiser. They’re fine for normal everyday care, but once you need serious specialized surgery or have a catastrophic illness requiring hospital care at a specialized hospital/facility like your husband, you’re screwed if all you have is Kaiser.