Sorry I should have been more clear, it's not that people will tweet "I have X, Y, Z problems with product" it's that they will tweet "@company Help me I have this problem".
This is basically because plenty of companies are doing this (see https://twitter.com/#!/vodafoneuk for example), so people get used to it.
So really it's not so much posting to a random website, it's more using social media as a means to contact them.
But based on the trend, people have come to expect it as the norm thanks to companies that lead the way in doing it, and now those compares are leading the way in proactively reaching out to customers who tweet not directly at them - for example 9 months ago I tweeted something like "As soon as my contract with Vodafone ends I'm moving to Orange", both companies tweeted at me offering to help - so people could well come to expect that as the norm too.
This is basically because plenty of companies are doing this (see https://twitter.com/#!/vodafoneuk for example), so people get used to it.
So really it's not so much posting to a random website, it's more using social media as a means to contact them.
But based on the trend, people have come to expect it as the norm thanks to companies that lead the way in doing it, and now those compares are leading the way in proactively reaching out to customers who tweet not directly at them - for example 9 months ago I tweeted something like "As soon as my contract with Vodafone ends I'm moving to Orange", both companies tweeted at me offering to help - so people could well come to expect that as the norm too.