iPhone purchased in Europe, now locked in United States

Unfortunately, your newly-purchased phone was apparently locked by the Spanish carrier’s network.

ONLY that carrier can unlock it to operate on other networks; although there’s not necessarily anything compelling them to do so.

This is NOT just a “European thing” … U.S. carriers follow the same practice.

Apple can’t override this feature.

See more detail here:

How to unlock your iPhone for use with a different carrier - Apple Support

Well it’s certainly odd.

If you purchase from a U.S. Apple Store … it’s unlocked … unless an AT&T installment plan is included.

Perhaps Apple in Spain has the same sort of arrangement w/ Vodaphone … ???

You’re welcome.

The general industry-wide lack of transparency on this matter is IMO quite distasteful.

Of course … “everybody” wants their inexpensive phone too.