At the start of lockdown my employer invested in Zoom licenses so they could control the settings at an enterprise level and provide integration with active directory and Outlook. We were already in the process of moving to Teams but they weren't quite there at the time.
We now have Teams working - but a lot of people are sticking with Zoom as it just works better an is easier to use. In particular for the way I work, Teams doesn't allow multi-screen use, where I can drag someone's shared screen to one monitor and still see the participants on another. We've also seen compatibility issues with cameras/graphics drivers that we don't see on Zoom. My Microsoft Surface Pro 3, for example, keeps losing its video on Teams but is fine with Teams.