Why require root to install on MacOS?

Initial setup
1

Why require root permissions to install e-mail client in 2024 on MacOS?

If, for some reason, there must be an installer, why not provide an option install just for one reason, without requiring root and doing god knows what on the system?

I know it might be Ok on Windows, but it’s quite not on MacOS.

I can see that question has been raised earlier, but with no response.

2

I can see that AppStore option is not on the list for some reason - however that would solve both root access and manual updates issue.