It's not sad, it's maddening

How odd. 'Sad' is a synonym for 'distressing' and 'unfortunate' and is used in that context in all of these examples. And saying the Indonesian tsunami is a sad thing didn't prohibit me from giving lots of money. Saying the number of abandoned and abused animals here in North Texas is sad hasn't stopped me from financially supporting my local no-kill shelters.

I so profoundly disagree with saying homelessness is not sad, or low-wage worker conditions do not make a sad situation. On the contrary, both are quite sad in the context of their present conditions, and denying that just to make a political argument belittles the empathy and emotions of those who say they find such things to be sad. IMO, it's splitting hairs on semantics just to feel better about one's own point of view at the expense of someone else's.

Now that's sad.

This is my whole point though. Situations portrayed as "sad" inspire charitable responses - as you note, when you saw a situation that you thought was sad (abandoned animals), you responded charitably, by donating money. But when we portray situations as sad, the general response is not to attack the underlying causes of the problem. And when looking at social and economic problems that DO have clear causes, and have economic and social policies and practices upholding them, we need to attack those root causes rather than dispensing charity. Charity is a great response to helping in natural disasters and other immediate crises, and I donate money to hurricane and tsunami victims like all decent people should. But it is not a lasting solution to deeply-rooted social and economic problems. And as long as "sadness" only inspires charity, I don't think it's a useful response to resolving social and economic problems.