These aren't typical "college folk" that we're talking about here.   They're wealthy young Asians living in a foreign country and likely have no desire to learn and follow all the local norms.  Much like American students on spring break in Mexico.  They also have an entirely different cultural relationship to dogs, with many treating them as disposable accessories rather than as "fur children" or family members.  

I don't condone the behavior, but these students aren't going to endure the hassle of dealing with all the property they've accumulated while here, especially if they have no plans for returning.  It's cheaper to just cut and run.  I also suspect there's a cultural aspect to accepting other people's "used" property.