Noting the time (2400-0600) and location of the incursion, I wonder how visible is the border at the time and location. Is it well-lit and visible from the air as something you can distinguish as the border? I know from watching news footage that some areas of the southern border look like the Berlin Wall, while other parts are an unlit dirt road with a fence.
It is all but invisible. So what? That's why you have to be sure of where you are when you wear a uniform and carry a gun. I spent much of the last year tooling around the Persian Gulf. The Border there doesn't exist. It's all water. I can guarantee that Iran would not take that excuse if I crossed into their waters and popped off a few rounds. Similarly I've taken a military vessel into Guantanamo. Do you think Cuba would care that navigation was hard if I popped a couple rounds off at their patrol boats?
Now should we start a shooting war the first time a neighbor mistakenly invades? No. Probably not. But I'd like to see some force concessions that are steep enough the Mexican Fed.Gov makes sure their pilots can read a GPS. If we start to see a pattern of careless incursions, some more lethal border protection would be warranted.
As we found out with U2's crossing borders is, or should be, dangerous. That encourages the crossers to be thoughtful about it.
Lastly, whatever we decide to do about illegal immigration and drug smuggling, we should publically end the farce that the Mexican government is our ally in either.