What explains apparent apathy towards social media activism?

I'm on the mailing list of a number of online activism (some might say 'slacktivism') platforms including GetUp, 350.org, Australian Conservation Foundation, the Climate Council, Change.org, The Greens, Avaaz. On any given week, I probably sign two or three petitions and roughly every two weeks I'll take more substantial action such as writing/calling a politician or donating funds to a campaign. I share most of these campaigns on Facebook and have been interested to see a trend of...well no response at all.

As an example, this weekend I shared seven posts. Two of them were petitions, two of them were non-actionable videos about advances/little wins, one of them was a terrible dad joke, one of them was a photo of me on a jumping castle and one of them was a non-actionable photo of song lyrics deploring Australia's current refugee policy. Guess which posts were most liked/reacted to?

My hope would be that the most popular shares would be the actionable ones. At least if people didn't like the proposed petition, they could have a discussion about it. But...drum roll please... the most popular post this weekend was the terrible dad joke (and I'm not even a dad):

Next most popular was the non-actionable whinge:

Then the photo of me on the horizontal bungee jump:

The petitions and success stories all got two likes or less:

What explains lack of interest in these actionable posts?

One conclusion is that my friends on Facebook are a shallow bunch, easily amused by bad jokes and reluctant to do anything more than whinge about societal issues. I don't think this is the case though. Of the 1275 "friends" I have on Facebook, a fair proportion of those are young, left leaning, progressive types. Survey research from the last Federal election indicates that this demographic is generally concerned about the types of issues that typically come up in the petitions I post (treatment of refugees, climate change, marriage equality, social inclusion).

Some other explanations are:

1. Slacktivism fatigue: My facebook friends have an aversion to "slacktivism"/"click bait" and avoid these kind of posts like the plague but are often taking action in the real world. This seems valid - I've seen comments that people are increasingly unsubscribing/disengaging from GetUp because "they want me to get angry over a new issue every week".

2. Facebook conspiracy: Facebook downgrades the priority of posts with a link to these sites in the timeline and as such, most of my friends never see them. This may have a kernel of truth. I rarely see petitions posted by other people on Facebook.

3. Mobile activism is tricky: given that many people access Facebook from their phones, maybe they are put off by the difficulty of filling out a petition on a mobile device.