Many employers only offer insurance from one source.
Kaiser is an attractive option for them due to its being generally cheaper, especially for small companies with only a few employees that are unable to bargain for lower group rates.
If they want to change providers, assuming their employer offers a choice, they will probably have to wait for the "open enrollment" period. This is usually once a year and they will probably be locked in to their current provider until that time.
There is no legal requirement that employers offer a choice in medical insurance, only that they provide it to employees that work 19.5 hours a week or more, for 4 consecutive weeks. The last qualification is how many businesses beat the requirement, especially food service establishments. You can work people for more hours per week, then cut their schedule, and as long as they don't average more than 19 hours a week, you don't have to offer insurance. Shitty, but true.
IMO this issue is between HPD and Kaiser/Straub. Those that have their insurance through them are being illegally burdened with providing "proof" they don't suffer from mental illness, when that burden is supposed to be carried by the state.
For those of you that feel that "this doesn't apply to me, I have different provider", think again. HPD could just as easily require this from ALL of us, with a change in "policy" if we let this slide. In fact, I think this may be the ultimate goal.
We all have a dog in this hunt.