It seems that
#Thunar (
#Xubuntu default file manager ) just can't get the .Trash folder to work with
#btrfs volumes using subvol
#mount option. That's quite a weak achievement. Because the
#swapfile must be on root volume, and therefore it's logical to use subvolume for all data, so it can be snapshotted. But if snapshots are being used, then
#trash feature won't work anymore, due to the limitations linked to the
#subvolumes. Yet I personally find this to be incredibly lame and totally pointless and completely unbased limitation.
#Linux silliness.