What good is Screen Time?

Set myself up as "Admin" on my kid's MacBook. Set up my kid as 'Standard" user. Re-logged in as Admin and enabled Screen Time. Set up restrictions. Tested them by logging in as my kid, but the restrictions I set up seem to only work for myself. Set up screen time in my kid's account and of course they can be turned off by my kid.

I thought setting up an admin account would enable me to set screen time globally for the Mac, but apparently I was wrong. I'm not really getting what Screen Time is good for – can anyone elaborate?

I should also mention I tried to set up Family Sharing and set up Screen Time with a child account. This was impossible, as it requires a PayPal verification and that only generates an error message, and there is no alternative method of verification available. Thanks Apple.