"Likes" are like currency that is virtually free of cost, and I think the younger crowd has no problem giving away likes. They don't have the stigma / fear of spam, data mining, etc. that the HN crowd does.

Please even the HN/Technology crowds don't have a fear of spam, data mining etc.

Gmail, Google Search, Twitter, Facebook etc are all widely used.

For everyone, it comes down to convenience

Its a pity that one of Facebook's main revenue source is promoting brand's posts, because otherwise it would seem like the best decision they could make is to outright ban any posts along the lines of "Like and share and comment on this to win a prize", both to reduce the noise on people's timelines, and to improve the quality of the like data they're collecting on users.

There's a similar effect on Twitter with brands asking for retweets, but I see less of those, presumably because the kind of people I follow on Twitter are less likely to get sucked into that.

I could be wrong, but I'm fairly sure some years ago FB had a rule that you weren't allowed to force people to like your page to enter a competition. Last time I had to set up a competition for a client (a couple of years ago) that rule didn't seem to exist so either the rule has changed, or I dreamed it.

Either way I'm glad I have nothing to do with that sort of work anymore. Having quite a few friends in agencies I see the X likes Y posts all the time because they have to like a load of brands for their jobs. What a miserable waste of time.

They can do better - they just don't show you them, unless the page pays to promote it.