Wageslave
They also both have a runway 11. One would assume that they were on a visual for 11 and thus saw Del Norte first. As for identifying one airport from the other in terms of size I would suggest that may not be as easy as you seem to imply, certainly from a distance. As the aircraft gets closer I would also imagine that the crew are concentrating on the runway (PF) and instruments (PNF) for call outs, and not admiring the surrounding scenery. Of course it would be interesting to know if they had set up their instruments for say an ILS or other type of approach which would have warned them that something wasn't quite right, but I don't know what aids the airport has.
Note: Del Norte Runway 11/29 is reported as 5049 feet long - though still ample for the Embraer.
Edit: From what I have found 11 has an ILS and there's a VOR-DME on the airport.