Here, once and for all, is the definitive answer.
Open the Impact Assessment for midata, turn to p.3 and read – it's all in there:
"Choice engines". What a phrase. Who won the office sweepstake last week for that one?*
What are the policy objectives and the intended effects?
Giving consumers access to their transaction data will enable consumers to make better informed decisions and choose products which offer them the best value. This in turn will reward firms offering the best value because they will be able to win more customers, increasing competition and leading to lower prices, improved efficiency and greater innovation. It will allow consumers to analyse and then improve their consumption patterns, particularly by enabling third party ‘choice engines’ to process transactional data on behalf of consumers and advise them on their consumption habits and potential switching options. We expect the release of information to stimulate innovation in and expansion of third party choice engines.
The idea behind midata is that you should store all your transaction data in a personal data store (PDS) hosted in the cloud, on the web, by a trusted third party like, say, Mydex. Some innovative juvenile writes an app which, given the evidence of your consumption patterns, recommends the best play to go to see in London. You give Mydex permission to share your data with WhatsOnApp® and a stream of unwanted phone calls ensues, trying to get you to see Chicago. Ditto health apps – eat more broccoli. And financial apps – earn more interest, save with Bear Sterns.
You've got to be a bit stupid anyway to open a midata account in the first place and store all your personal data in the worldwide wild West of the web with a third party you've never met and have no reason to trust. Even more stupid to go on to share your personal data with unknown third party apps.
But then, you are stupid, aren't you.
That's what BIS must assume. You're the sort of person who can't choose what clothes to buy for the Summer without having an app to help you, see A midata future: 10 ways it could shape your choices.
Advocates of midata are forever promising an "ecosystem" of apps developers. That's not the answer to the question. They're more likely to create a natural habitat of the stupid.
* Probably DMossEsq, come to think of it, see Have you ever had breakfast with Sophia Loren? (2003), p.81:
The choices made,
the preferences expressed,
are a function of my personality,
if you like,
of my character.
That's using your language.
In my language,
personality or character
is a choice engine.
And choices are made to maximise rewards.