Hmmm... haven't read those regulations (I know perhaps I should but currently I have enough spanish legislation to read) but let me see if I can clarify a bit.
Senasa (the only atco formation centre in spain) had untill 2010 an agreement with Aena (the only ANSP in spain) to train atco students with no cost to them and after completion they would be offered a position at the ANSP. Similar to NATS or other serious providers if I'm not mistaken.
After 2010 several training centers opened, for example the UCJC who trained a few atco students (I'm not sure how many... between 50 and 100 I believe) in UK who then found out that their licence was not valid in spain...
Aena has not hired a single atco since march 2010... all those willing to pay these fees at Senasa (or the other training centres) have mostly wasted their money. Just a very limited amount of chosen ones have made it to the other ANSP now working in spain, FerroNats (there is another one, Saerco (no, not Serco)) working in the Canary Islands). Their working conditions have already been mentioned in this thread.
So FerroNats just recruited whatever was available, be that atcos with foreign licence, military personell, recicled AFISOs (you don't want to know about these... trust me) or those poor sods who just paid 50k euros