Install app via user account (not as an admin)?

Perhaps I have had a false impression. I thought that you could not install apps while logged in under a standard user account. I thought that standard user accounts could not install apps ... and that if one tried, you would have to authenticate as an admin in order to install an app.

Or perhaps I just discovered another Zoom security issue? I was logged into a standard user account (purposely) and ran the Zoom installer package. It promptly installed Zoom, no stop for admin authentication.