One Alameda County supervisor implies that perhaps he could have gotten them open by May 18th. I doubt that because the power to do so is not directly invested in the board but rather the county health officer. The health officer is acting in concert with the other counties health officers.
The leader of this group is the Santa Clara health officer, Sara Cody, who has been credited with architecting the lockdown. The officer has been very vague about opening the counties up to phase 2, saying that it will be frustratingly slow (a).
The officer points to insufficient testing and insufficient numbers of workers to contact trace (b). The officer said that they are weeks away from having enough workers to contact trace and that tests are only 20-25% towards the goal.
My issue with the tests are that they are voluntary. There is probably no way to meet that goal unless you force people to test. You can tell by the number of tests in each county. It isn't really going up very fast (c). At present rate, you are talking about several months. The issue doesn't seem to be insufficient tests. It seems to be mostly that people aren't going in to get tested since the positivity rate is actually going down.
I also think that the health officers want to work in concert since one county moving faster than the others will create pressure on the other counties to move at that rate. There is already such pressure since the rest of the state is already moving faster.
A good percentage of the Bay Area is insulated from the effects of the lockdown since many can work from home. The big tech companies have been relatively unaffected by covid-19. Government employees are still being paid. However a good percentage are not insulated by the effects of the lockdown (although it has partly opened up).
So based on the above, I expect the shit to hit the fan.
(a) https://www.sfgate.com/news/editorspicks/article/Sara-Cody-B...
(b) https://www.sfgate.com/news/editorspicks/article/Bay-Area-re...
(c) https://www.sccgov.org/sites/covid19/Pages/dashboard.aspx#ca...