>I'm not too keen on the people in the cars who recommend opening fire on the migrants etc.
I agree, that's just as ludicrous.
>No-one would choose to be wandering around a highway trying to sneak into the back of a truck if they felt they had a better option, and the lack of empathy is as depressing as the sight of all these people wandering around.
That's true, but desperation isn't the entire story. Not all desperate people behave this way. I think a big part of is just the difference in culture; road laws aren't respected pretty much at all in a huge part of the world. My experiences in India come to mind, where right of way is determined by games of chicken, crosswalks are irrelevant, intersections are a madhouse, etc. It's not like migrants are required to take classes on traffic laws, regulations, and customs before they're allowed into the country.