I've always suspected journalists can get a biased impression from sources like social media, because normal people don't go on social media to brag about how good they have it or say how much they love their employers (except perhaps on linkedin).
If my waiter buddy posts about how he's had a shitty day with rude customers and his boss cancelling his holiday because they're short-staffed? I might say "oh man that sucks - work, amiright?"
I'm sure as hell not going to chime in and tell him I'm highly paid with interesting work and great conditions.
I can easily see how a journalist, viewing Twitter or Reddit or Facebook, could come to the conclusion that everyone hates their jobs.