People will choose convenience over privacy when they can't see the threat. Zoom is convenient for video calls because it allows you to see all the people in the call on one screen, you can schedule meetings, the connection quality is good, it supports screen sharing and it's fully cross platform.

You already disqualified Facetime because realistically some of your friends and family have Android and Windows. WhatsApp connection quality is flaky, same with Skype. Does signal support group class? If it does maybe it could replace Zoom. Maybe. But all these options existed before lockdown and people still settled on Zoom because it's more convenient.

Either some massive scandal has to happen to make the public more privacy conscious or there needs to be e2e encryption by default, as a standard. With or without invisible state surveilled cameras shouldn't factor in to which dining table I buy.