Virtually all retailers now require barcodes regardless of mass produced of hand made. Barcodes can be useful as the number is often the EAN international product code which can take you straight to the maker. Not sure when this system went universal but 13 digit EAN prob by 1990s. This one looks like a 12 digit UPC which started in the 70s.
Should be various look up sites around for those with < 13 digits. For 13 digits you can use eBay' s sell item.