You can add the server to the call even if it is E2EE. You don't need to physically show it as a separate user and the client can hide that information and make it seamless.

Sure, you COULD or you could just encrypt between client and server and be done with it.

Business users are their focus and outside select industries, vast majority of businesses don't care if government is spying or not. Heck, most businesses would turn over information to government without any fight. It's just not something they worry about.