My question is why doesn't it show lost/stolen status.
Same reasons. The phone does not have an Internet connection to report on its status.
You might have requested that the phone be placed in Lost Mode, but you cannot confirm that this occurred unless you actually saw the change in status status in Find My when you requested that the phone be placed in Lost Mode.
On the other hand, it is possible that the phone was placed in Lost Mode when you made the request, but the Internet connection was lost shortly thereafter, so the true status of the phone remains unknown at this time.
Apple states it this way:
When you mark a device as lost, it won't appear online and in Lost Mode until the device is turned on and connected to Wi-Fi or cellular.
If you try to log on using Find My again.........do you see a message the phone is "Offline"? If you do, the current status of the phone cannot be known.
If you did not actually see the status change when you originally tried to enable Lost Mode on the phone, then Lost Mode was not implemented.
Unfortunately, you won't know much at all about the phone's actual current status unless and until it has a reliable Internet connection.
Unfortunately again.......iPhone thieves know this.