That's patently untrue. Micropayments haven't taken off because it's impossible to make money on transactions less than about fifty cents.

If the transaction processing costs were 0, do you suppose this payment system would still continue to not exist?

I do. I believe the fundamental issue is one of user experience. I think if you force the user to make an affirmative decision to pay every time they want to read an article, a huge number will not bother, even if the cost is negligible. Especially since there will probably be 5 other news sources who are "summarizing" the same content for free, with ads.

There are very few things that are worth 5 cents that you'd get me to pay for that I couldn't just do without.

That wasn't the question; what percentage of the economy is from purchases that fall into the category of "I could do without"?

The question is, the NYTimes article linked on HN with 120 comments... would you pay 5cents to read it?

The decision to buy can definitely be irrational, but that can cut both ways. Buyers might decide against purchasing even when the product is clearly affordable.

Consider the Facebook social reader apps like the Washington Post. If you click through from your Facebook news feed, you need to authorize the app to read the article. It's a one-button form, it's totally free, and you could revoke the app whenever you want. And yet, a huge percentage of people cancel out of it.

Would I pay 5 cents to read a NYTimes article from Hacker News? Maybe yes, maybe no, depends on the article. The point is that I would be forced into my "purchase mindset" every time.