Let's look at it from a different perspective.

Would an open-source self-driving car be safer than a closed-source version?

Possibly.

Why?

Because a lot of testing is required in order to make something like that safe. For one, you need to have or build a car with all the required sensors, servos and computers. Of course, this is not impossible. It does limit the number of available hackers to those who can afford to build such a car. Let's say, for the sake of argument, that this car costs US $50K to develop. If the hacker doesn't want to modify his/her own car an additional expense of US $15K to $25K would be added to this.

Yes, much code could be developed in a simulator, but as any micro-mouse competitor can tell you, there's a vast difference between a simulator and real-life. Ultimately, to make something better, safer, faster and more intelligent, real-life testing is imperative.

Any time you touch the real world things get expensive and slow. That said, a dedicated small group of hackers around the world with at least $50K to burn and lots of free time could work on an open-source self-driving car. And the code may or may not be better than the closed-source. Open-source doesn't automatically mean "better", "safer", "faster" or "more intelligent".

Now, switching to the pacemaker question. What does it take to develop an open-source pace-maker that doctors can and will actually implant. I don't know. I am not in that field. My guess is that the cost is in the millions. Sure, one could screw around with code and ideas and pretend to be building a pace-maker. In the end, when all the smoke and bullshit clears out, you have to implant the thing in a living organism and test it. Multiple times. And, you will kill some of your subjects. Or you are likely to.

How many hackers can do that? Probably not many.

Then there's the issue of regulatory testing and FDA approval process. That is a very expensive process. Who would undertake that?

The point is that open-source is great when it is confined to code running on a commodity device. In terms of the financial investment, it costs exactly zero for someone to decide to make another javascript library. Why? Because for that person to even consider doing so it means that they already own a computer and probably know javascript very well. How many non-coding backhoe operators who do not own computers decide, overnight, to develop a javascript library? Exactly.

Yes, there are a lot of open-source/open-hardware projects, but they are absolutely trivial in comparison to a pacemaker. Implanting something into a human being is a big deal.

Then you have to look at the patient's perspective:

Doctor: "Mr. Obama, you need a pacemaker. We have two choices. First is this pacemaker developed by big-bad-established-closed-source company that makes too much money. You also have the ability to use this model, developed by fifty guys all over the world and it is open source"

Obama: "Who are these guys?"

Doctor: "Hackers who believe that open source is a better way to build a pacemaker. The argument is that the code and design are completely open and, hence, bound to be scrutinized by other hackers to a degree that closed-source can't even begin to approach"

Obama: "Yeah, but, what guarantees do they provide? Who is the responsible party? What recourse do I have if something goes wrong and I need serious help?"

Doctor: "Well, there's a company that sells them. So, that's your point of contact. No different from the big-bad medical company".

Obama: "C?"

Doctor: "Nope, C++"

Obama: "Preemptive?"

Doctor: "Round-robin"

Obama: "I don't know. I'm kind of concerned. Let's go with the closed-source version. I don't know if I want to trust my life to a bunch of hackers around the world."

Dumb example, but you can't ignore the last issue with these things. RMS might be more than willing to experiment with his own life (I wonder). This is certainly not the case for Joe Average. Given the choice, they'll probably opt for what they perceive as safer and more reputable, rather than the hacker version. As much as folks in the tech community might understand the value of open source, the aforementioned non-coding backhoe operator who doesn't own a computer will have absolutely no intellectual connection to the concept of open source. All he will hear when given the choice is that a bunch of pimple-faced teenagers in their underwear developed this pacemaker in their bedrooms and experimented with their dogs. He'll opt for column A out of fear.