When does the Software Updater request a password to install updates. Sometimes I am asked for a password and other times I’m not, so I’m wondering what triggers it.
You need to enter your password for anything that involves an installation to Root.
For the security and safety of the system, anything going into Root must be authenticated by the administrative user- In this case, You.
Furthermore, if you choose to use the Synaptic Package Manager, (Which I Prefer) it will ask you for your password on every start of program launch, that gives you an extra level of security.
FYI, you won’t find the security levels of Linux on a Windows system. Windows will do what it wants, when it wants, and load up apps, you don’t even know its loading, its an insidious OS compared to Linux.