Why does MediaPicker.CapturePhotoAsync() need StorageWrite permission?

[NathanielJS1541]

On Android, the CaptureAsync method of MeidaPicker.android.cs has the following code:

// StorageWrite no longer exists starting from Android API 33
if (!OperatingSystem.IsAndroidVersionAtLeast(33))
    await Permissions.EnsureGrantedAsync<Permissions.StorageWrite>();

I can't see why this is needed, as the captured photos are just saved to the CacheDir, which shouldn't need external storage permission.

In an app I'm working on, we're required to provide a popup for each permission request explaining the permission, and I'm finding it hard to justify the StorageWrite permission as I can't understand why it's needed myself.

Can anyone explain why the StorageWrite permission is required?