> I don't like closed systems that I have no oversight into, into what they might be logging, etc.

I’m going to be generous and assume you’re both diligent and technically competent enough to inspect all the security-relavant open software you run - henceforth I’ll speak more generally of you as an arbitrary person.

If we take your view in the abstract, it’s incorrect. In the abstract, you do not have any more oversight over open source software than you do closed source software. You could have that oversight, in the same sense that you could run a 5K everyday, but if we’re being realistic, you do not.

In theory this perspective makes sense (“many eyes make all bugs shallow”), but in practice virtually no one actually examines what their open software software does, which means it’s not actually very helpful - you don’t have very many people picking up the slack for you either. This provides a false sense of security in my experience, because we’re talking about the world as we’d like it to be, not as it actually is.

What I usually observe is a curve - the modal company’s software is less secure than a large open source project, but once a company’s software has any appreciable fraction of comparable open source software (i.e. the company matures), the curve flips and the commercial software is more secure. From what I can tell this happens for two reasons: 1) once open source software hits a certain critical complexity point, it becomes exceedingly difficult to review effectively, and 2) the best and most qualified people for this work can get paid significant, double-take amounts of money for doing it, and are almost entirely employed by large companies. The result is that software like iMessage is some of the most secure that exists in its category, which essentially no fully open source solution can hope to compete with, because it simply lacks the same organizational direction and experienced talent working on it.

I think a small subset of all open source software has something close to idyllic security and organizational direction, typically the software used by sufficiently many people that real talent is drawn to look at it too. Project Zero looks at software like this. Beyond that, there is an extremely long tail of open source software projects (approximately all of them) which are used by a nontrivial number of people but which 1) will never receive a serious security assessment, and 2) will be more insecure in perpetuity than commercial alternatives once those alternatives have had 1 - 2 competent security reviews. Before those reviews, I’d say it’s probably a toss up of two equally suspect options.

In any case, the reason I’m responding with all of this is because it’s something I see pretty commonly repeated that I think doesn’t reflect reality. I hate to be so maximally capitalist about this, but if you’re optimizing your software for security, you probably want to use something produced by the resources of a large company. The best of both worlds is obviously a mature open source project officially developed and sponsored by a large company, but when that fails, I would personally choose closed-source solutions most of the time.