Vokes - the positive test cases reported by the Department of Health do not include the number of people staying at home while coughing away. The question for Spain is whether 2,000 cases per day represents a very small tip or a large chunk of the iceberg. If 2,000 positive tests is accompanied by another 2,000 other cases which weren't identified, then it's still 1 person in 94 A320s - ie an acceptable risk. If the number of unidentified cases is significantly more, then Spain might want to be more cautious.
The other factor is the capacity of hospitals to deal with a local spike in Covid cases. I suspect that the likes of Madrid, Barcelona and Valencia could cope, but somewhere like Lanzarote or Mallorca which have modest year-round populations combined with a seasonal surge of mainly healthy people (people who are ill tend not to fly) who typically need just minor treatment (bumps, bruises, etc) could not, thus a greater need for caution