healthy risk?

Last weekend there was an event run by Renewal in our neighborhood.  This is an organization devoted to encouraging people to donate kidneys to those who are in need of them.  Sounds like a good cause, and it is supported by many Rabbis in the neighborhood.  But here is what I don't understand.  Kidney donation is a RELATIVELY low risk operation -- but low risk does not mean no risk.  The odds of death are about .07%, the odds of other complications from the surgery greater.  Your seichel should tell you that walking into a hospital for an operation is not the same as a walk in the park.  So how is it that this risk is an acceptable one for a person to even voluntarily enter into, but we had to close down every yeshiva and every shul last year, not even allowing young healthy people to come together to daven, and even ad ha'yom ha'zeh I can tell you there are shuls in our neighborhood still holding minyanim outside in tents with young people wearing masks and still sitting 6 feet apart?  If you want to argue that in the former case there are dire, serious consequences if someone does not get that kidney that they need, are there not also serious consequences to closing down shuls and yeshivos?   Do we need the NY Times to tell us about the devastating effects lockdowns have had on school children (which was pashut l'kol bar bei Rav m'ikara and useless to bemoan after the fact)?  Is the fact that we have to have campaigns to come up with ways to entice people to return to shul not enough proof of the damage done to the communal religious structure in many communities?  Is the chiluk the % of risk?  If so, as I've asked before, where exactly do you draw the line and what is the makor?   What makes taking a .07% chance of death halachically OK, but some higher point-something-or-other not?  The only standard I've seen is "follow the doctors," which means follow the doctors we (whoever "we" is) think are authoritative as opposed to the ones you do.