I think another factor to think about with this comparison (it's actually a really good comparison) is that typically side effects will be known for the medicines, usually via trial runs of the medicine.A sort of comparison that always comes to my mind is prescription medications. New Prescription medications are prescribed to millions of people every day. A small percentage of the people that take these medications will have horribly adverse reactions to them. Some could die, have strokes, heart attacks, develop cancer, etc. But that doesn’t stop them from being prescribed by health professionals everywhere by the millions day in and day out. They know that the benefits received from the medications will far outweigh the negative effects. This is a case where a medical professional has to weigh two health outcomes and determine which is the lesser of two evils which is entirely in their wheelhouse to do. Prescribe and let no one gain the benefit of the medication to protect anyone from adverse effects or vice versa? But this situation is different medical professionals can’t weigh health outcomes to people losing jobs and becoming homeless, or kids falling behind in the entire country in school to the detriment to the future of the entire country, etc. That’s my concern, no one’s wheelhouse is equipped to weigh both and make logical decisions.
For COVID we don't necessarily know all the side effects. It could be there are no other ones that will come forward. It could come forward that (going over the top and exaggerating here) your brain will literally melt 3 years after contracting it. Instead of opening and saying let everyone get it, CA seems to be playing it safe and trying to delay reopening until there is a vaccine (which could also have issues).
What we don't want is another thalidomide issue at hand (be it from COVID itself or a vaccine).
(For those unaware, thalidomide was an anti-anxiety medicine mass marketed outside of the US [the FDA refused to approve it citing the need for further studies] that caused large amounts of birth defects.) [further reading (graphic warning)]