The #1 problem is lack of education. A large number of software developers have had no formal training in software development. Almost all who HAVE had formal education don't receive any education or training in how to develop SECURE software.
I teach a graduate course at George Mason University (GMU) on how to design and implement secure software. So there are people who are learning, but there are many more to go.
For the most part, countering the OWASP top 10 doesn't cost more, so cost has nothing to do with it. At the high end of security requirements it definitely costs more, but stuff like parameterized statements (countering SQL injection) and using web frameworks that automatically counter XSS injection don't cost any more.
There's a few other things which are worth taking a look at on the topic at http://internetofagreements.co... - the HBR piece is short, and this is not a topic that is particularly easy to compress.
There are two things in particular that didn't come across well. Firstly, we expect this to be a five to ten year process. We're well aware how much there is to do, and how far this all has to come. We don't dream you can just digitize a body of law through natural language processing and then have an AI make legal rulings any time soon. But narrow areas - product labeling comes to mind - might be high value and tractable quite soon. And Internet of Agreements blockchain. Blockchain is a *how*, but IoA is a *why*.
Second thing is that IoA's intention is to get people with various pieces of this picture into direct contact with each other, with a rough sense of the goal state in a decade or so, to start building the bits that are currently financially possible to do real engineering on. As time passes, more and more of the vision should become manageable, and things will pick up speed and come together.
Hope that helps.
If computers take over (which seems to be their natural tendency), it will serve us right. -- Alistair Cooke