SIP is different. Apple explicitly built these tools with mechanisms to turn them off, for users who wish to do so.

If there’s a Microsoft-created mechanism for disabling automatic updates on non-pro (!) editions of Windows, I would love to know about it. All the methods I’m familiar with are weird hacks that have side effects or don’t always work.

You can disable Windows Update by changing the states of all its services in the registry to "disabled". To my knowledge, this doesn't have any side effects. Updating just no longer works unless you turn the services back on, plain and simple.