A number of countries have already done this and it’s not definitive that changing to opt out systems will make a noticeable difference in actually donated orga

A number of countries have already done this and it’s not definitive that changing to opt out systems will make a noticeable difference in actually donated organs. Most of the “this is so obvious!!!!!” studies that promise huge results are actually looking at registration numbers, but if you die in a way that makes you a good donor option, the doctors in most places will ask your next of kin about it whether or not you are registered. In some places the next of kin can even override your opt-in (or failure to opt out). So social education/opinion campaigns that increase registration and influence potential next of kin could be a better move than going opt-out.