Find My iPhone (Stolen)

Hello everyone,

A couple of days ago I had my iPhone 13 pro Max (os 15.6.1) stolen in Milan city center. Find My iPhone and Find My Network were enabled, but I couldn't locate my phone till a couple of hours later when it was turned on, unfortunately just for few seconds. So I followed the procedure indicated here by apple (If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support) and I marked it as lost and I request to erase it.

The day after the thief turned on my phone, I saw the location and I called the police that in few minutes was there. They asked to me to play a sound on it, but I couldn't because the phone was erased. So I lost my last chance to find it.

Now my questions:

1. Why Find My network didn't work? The thief for sure walked in a place full of apple devices
2. Since it is clearly written on the support page

"If you erase a device that had iOS 15, iPadOS 15, or later installed, you can still use Find My to locate the device or play a sound on it."

How is possible that I wasn't able to play a sound on it or to locate it because it had been erased? Did this happened to someone as well? On the ss below you can see that

"The location of this iPhone won't be updated because it has been erased"

Thank you,

Giuseppe