Young adults have provided some of President Obama’s staunchest support — despite the accumulation of bad economic news for young people documented by groups like Generation Opportunity.

Now Megan McArdle ponders in a Daily Beast article how “rate shock” associated with ObamaCare will impact those young adults.

The most basic reason that rate shock matters is that I don’t think young single people were expecting it. It’s true that during health care reform, the reformers acknowledged that some people would end up with a big health insurance bill they hadn’t had before. But I wouldn’t say that they exactly emphasized this aspect. The implication that I, for one, took away from their analyses was that the subsidies would substantially reduce the cost for even quite middle class people. Maybe a successful young IT contractor living in a nice condo would have to pay a few thousand dollars for the insurance he hadn’t been buying, but I was under the impression that your average scraping-by clerical worker would pretty much have their bill covered, or reduced to some negligble sum.

So I got a sort of a shock today when I started playing with the Kaiser Family Foundation’s subsidy calculator. I had it at the back of my mind that a single young freelance writer living in California, Washington, or New York, and making $32,000 a year, would qualify for insurance at a basically nominal cost. (The profession doesn’t matter so much, but for obvious reasons, this is a type that I’m particularly familiar with.) It turns out that this person will qualify for a subsidy of about $213 a year, based on an expected “Silver Plan” (the medium coverage package) cost of $3,018, or about $235 a month. …

… Anecdotally, they seem to be expecting the kind of generous package that Mom and Dad have, at around the cost of their monthly cell phone bill. I don’t think it’s sunk in that Obamacare will force them to pay $150 a month for insurance similar to bare bones plans that are available right now in many states for $100 a month–which they’ve declined to buy. And I’d be willing to bet that the average childless adult making $32,000 a year is expecting the government to kick in a lot more than $18 a month towards the cost of this suddenly-more-expensive insurance.

Why were they (and I) expecting more generous benefits? Because discussions of cost, and subsidies, tended to be focused around the hypothetical family of four. Families of four qualify for subsidies at quite high incomes–up to almost $95,000. That made it sound rather broad based. But for childless singles, the income range that qualified for help is much smaller. Effectively, a childless adult with a college diploma, or for that matter, a trucking license, is unlikely to qualify for more than nominal assistance in paying for health insurance.

But how many young, single people are there? Is it really enough to worry about what they’re expecting?

Well, according to a 2009 brief from Kaiser, childless adults compose almost 60% of the population of uninsured.