Trust in and maintenance of filesystems

> my impression is that modern GNOME doesn't automount (you need to actually click the filesystem to get it to mount)

In my experience, it does automount hotplugged USB storage devices, going as far as asking for the LUKS password when the device is encrypted. I don't know if it has a whitelist, but at least VFAT, ext4, XFS, btrfs, and the CD/DVD filesystems (iso9660 and UDF) seem to be automounted.