the reasons the Best Before Dates are marked like this, ie on label, for Best Before Date see cap is simple really.
The labels are printed in thousands, hundreds of thousands, probably in a spearate location to the bottling plants. As the products are being packaged, ie bottled, the individual lids are stamped with the batch number and BBD, This is usually on the top and process occurs when the packaging process is complete. This would also be the case with cans etc where thousands are produced empty, and then stamped with BBD on completion of package.
Hope this helps end crazyness