Stolen Iphone

It’s not weird. Unfortunately, like any tracking service you have to have the required feature (in this case “Find My iPhone”) on to work (it’s the same for any service, not just Apple). Otherwise imagine the privacy concerns if your carrier was actively tracking every move you made 24/7. It’s also required if you had AppleCare with Theft and Loss to file a claim. I’m always surprised by how many people don’t have it on but can’t understand why their phone can’t be located without it. Was it stolen or was it misplaced? If you have an idea of where it was stolen from and possibly the people that were around when it came up missing that would hopefully be helpful when filing a police report. Other than that though it’s likely lost until someone realizes they can’t use it (assuming it’s not someone that knows you and knows your Apple ID info).

You can't.

Report it to your cellular carrier and the police.