There are three things every 9-year-old loves: Legos, soccer and single-payer health care.

Okay, maybe that was just me, and possibly Bernie Sanders. He, of course, has just introduced his own Medicare-for-all bill. It's the kind of thing I was apparently stumping for back in third grade.

That, at least, is what I found out when my dad dug up a particularly hard-hitting editorial I'd written for our class paper back then.

Now, for whatever it's worth, it's quite possible that I understood health care better back in 1994 than President Trump does in 2017. Not what co-pays or deductibles or premiums are. But the basic idea that everyone already ends up paying when someone without health insurance goes to the ER — hospitals get taxpayer subsidies for treating them — so we might as well help them get insurance in the first place. And that the easiest way to do that is for the government to simply give it to them. You could even call it something catchy like “insurance for everybody.”

Which brings me back to my third-grade class. Beyond learning multiplication and division and reading a lot of Roald Dahl, we also put on a two-week-long mock city. You could go into business for yourself selling homemade cookies or trinkets or whatever else you thought 8- and 9-year-olds wanted to buy with fake money, or you could get a job from our teacher, Ms. Shainis. I was the newspaper editor.

Now, to add a little realism to it all, the last thing you had to do was decide whether to buy faux health insurance to protect yourself from faux health emergencies. Every couple of days, you see, Ms. Shainis would pick a name out of a hat to get hit by an alphanumeric (“W350” or “W390”) medical emergency. If you had insurance, you were fine. But if you didn't, you'd most likely get wiped out and be left with a substantial medical debt to pay back.

Nobody said third grade was all fun and games. Especially not for the two kids who took a chance going uninsured and ended up going bankrupt.

This was the type of story the Cocoaville Gazette — that was the name of our paper — didn't shy away from. Well, that and where cafeteria food came from. (“The world may never know,” one of our writers concluded in a story admittedly short on reporting, after recounting the traumatic time she “found four hairs” in her salad.) So I asked the question that 15 years later would dominate American politics the same way it had Ms. Shainis's third-grade class: “Should” people “have mandatory health insurance?”

As a practical matter, 9-year-old me said yes. After all, everyone was worse off when someone couldn't “buy any products in Cocoaville,” because they had to “pay for the cost of their disasters” instead. So simply for “the good of the economy,” I thought that “health insurance should be provided to everyone, and paid for by increasing taxes.”

Twenty-three years later, there are a couple of things I'd add to this. The real world, it turns out, is both more and less complicated than my third-grade class. More complicated, because it isn't so easy to go from a private insurance-based system to a government-based one. It's not just that insurance companies would quite literally fight to the death against Medicare for all. Or that some hospitals would as well for fear of following their best customers — private insurers — into financial oblivion. It's also that everyone who's happy with their doctor wouldn't want to risk that for something they might like just as much.

Which is to say that health care tends to be path dependent: It's hard to change systems once you already have one in place. If you start out with a private one or a government one or some kind of hybrid, that's what you'll end up with. And that's fine. I'm not as dogmatic about single-payer health care as I was when I was 9. Universal coverage is what really matters. Single-payer is one way to get there, but it's not the only one. You can regulate and subsidize your way there, too — basically a beefed up Obamacare — with private insurance. That's what Germany and Switzerland do.

But what's less complicated is the case for universal coverage. Indeed, that's stronger in the United States today than it ever was in my third-grade class back then. Why is that? Well, when I was 9, I didn't have to worry about having a preexisting condition, or not being able to afford insurance, or using it all up. Health insurance was the same, low price for everyone, and it safeguarded you from whatever fate might be lurking in Ms. Shainis's hat. So if you went bankrupt, it really was your fault — hence my strictly utilitarian defense of universal coverage. It was about ending the unfairness of responsible people being hurt by the irresponsibility of others.

That almost seems quaint, though, compared with the unfairness of responsible people being hurt by the immorality of the system. Of people being priced out of the insurance market because they had a preexisting condition such as acne; of people having their policies retroactively canceled because they hadn't disclosed that they'd ever been short of breath or incontinent; of people having their insurance run out on them, because they were too sick and had hit their lifetime limit on benefits. That was the way health care worked before Obamacare, and it's the way Republicans want it to work again. Not everyone would be able to buy insurance, and not everyone who had insurance would actually, you know, be insured.

So even if we weren't covering some of the cost of the uninsured going to the ER, there'd be a strong case for helping them get insured: It's the right thing to do. You should be able to buy health insurance even if you wouldn't be a profitable customer. You should be protected from medical bankruptcy if you do have insurance. And if we can't figure out how to make the private sector do all that, then the government should.

Health care, as Trump recently discovered, is complicated, but not so much that a 9-year-old can't understand the basics.