This is yet another boring subject which pops up from time to time on this forum. Because this forum is predominantly read by Brits and Americans they base their opinions on the very strict rules applied by Britain and the USA. I have mentioned several times before that there are many nations around the globe that do not promote such draconian regulations on their aircrew, with the exception of when they are flying to the USA. It is certainly not uncommon to see "passengers" on the FD of many non-British/American carriers in European skies. Generally these will be persons that are either personally known to a crew member or who may have professional aviation credentials. It is left at the Captain's discretion, as was always the case in the past. I have made several FD visits and landings on European carriers in the past 10 years. They are not breaking any individual company SOPs/rules by doing so. In answer to the OP's question I can say that it is definitely par for the course on most Spanish carriers, as it is with many from other countries too. They do however respect and enforce regulations set by the USA when in their airspace for instance.