You are right, but the main problem in MAD is how to go to the GATE without a boarding pass.
Aerolineas Argentinas Captains are usually very nice guys but their regulations don't allow them give jump seats to other company pilots, so your only chance is to go to the gate an ask in situ the jump seat.
Air Europe and Iberia could be much better.
One of my best friends is flying for Ryanair and he had to fly from EZE to MAD but without ticket, so We went to the terminal and he asked to the Captain just when he arrived for taking the flight.
The Capt was very nice and he asked a courtesy boarding pass for my friend and the ground staff gave it to him without any comment or problem.
Spanish Captains are GOD in their companies, in my company that's impossible.