Trespassing and robbing are two different things. These guys were rummaging through the victim's vehicles so I'm guessing that they just didn't happen to be wandering around lost.
In any case, thieves are now showing up armed. Colton Boushie was armed and it seems like the guy who carried out the recent theft in Saskatchewan* was likely armed also. I know reference the recent break-in attempt at my place that the thieves were armed...
* http://www.cbc.ca/news/canada/saskat...earm-1.4576216