Zero trust requires network visibility
In a zero-trust environment, trust is not static. Behavior has to be visible for trust to persist.
One of the most important differences between old thinking on networking and the zero-trust mindset is the inversion of thinking on trust. Pre-ZT, the assumption was this: Once you get on the network, you are assumed to be allowed to use it any way you want until something extraordinary happens that forces IT to shut you down and remove your access. You are assumed broadly trustworthy, and confirming that status positively is very rare. It is also very rare to have that status revoked.