FL TX and AZ experienced peaks and fell at roughly the same time as SoCal despite not "everything indoors" being shut down.
Testing and trace is dead if you aren't going to test the asymptomatics like the CDC now suggests. Otherwise you are left with a 14 day quarantine for anyone that comes into contact and people aren't going to do that.
It's not herd immunity...the prisons and now the new HK study have shown there's no such thing. After 20% though everywhere threshold has occurred things begin to slow down. It's a soft barrier that reduces cases to a more manageable place.
And yes we see now from Italy, Spain, the Neatherlands and Germany that any reopening before you get to that 20% will cause an acceleration. The decision we have to make now is, if we will be dealing with this for years, what we do about it. But if the HK study is right lockdown until vaccine isn't an option and neither is just let everyone get it and get herd immunity.