Pics / Content - Legal question

How sites like huff post,lifehacker,buzzfeed and the 100's of others use content and images like that?
I mean seriously, its not like a small site. fuck1ng alexa<1000...

I never care about pictures i put in my sites, so I just take them from where ever I find. but those sites have a "little" more traffic ..

What's your thoughts? they just risk it?

(btw not talking about normal pictures, obviously they have sub's for shutterstock or some other image provider for normal pics, i'm talking about pics from fb/personal sites/forums etc)

oh and add elitedaily, another one I didn't know but just found out