FB doesn’t show you everything. It realises that we’d all be spammed to oblivion if it did that. So it shows you what it thinks you want to see. This is based on your interactions with those people. For people I’ve chatted to a lot, it alwyas shows me their stuff – with other pepole less so.
I think when it says Fred Bloggs via John Smith – you are friends with John Smith and they have actively shared (ie clicked on ‘share’) something from Fred.
Whether or not you see the things people share depends on how you’ve interacted with them in the past. Or the content. I get lots of shares from someone I’ve friended on here, despite only having chatted sporadically – I think because that person mostly shares stuff about bikes. This part of the system works well, since I am naturally more interested in the bike stuff 🙂
You can ‘train’ FB in what you like by actively selecting ‘I don’t want to see this’ from the little arrow on the top right. I think there’s also a page you can go to that’s labelled something like ‘improve what FB shows me’ where it shows you sample stuff (both advertising and freinds) and you say how interested you are in it.
It’s worth doing. Facebook works much much better when you take control of your content.