I think it's important to look at these things in the context of the features they're enabling and user expectations. The fact that Zotero is a local, configurable, open-source tool is what gives you complete control over it, but it's not just a local database. It's deeply connected to a world of constantly changing websites, metadata sources, and services, and using most of Zotero's features implies relying on those things. If you want to save metadata from a website, Zotero might need to retrieve metadata from Crossref. If you want it to find an open-access PDF, it needs to connect to an online database to check for one. And if you want saving to continue working as sites changes, it needs up-to-date translators. From a normal user's perspective, the alternative is just Zotero not doing the things they downloaded it to do.
> My own understanding of privacy best practices, includes data exposure being opt-in rather than opt-out
Surely you don't expect software to default to not receiving updates automatically? As the linked section says, if you disable translator/style updates and don't use auto-sync, there won't be a persistent connection. But if a high-profile site breaks and we roll out a fix, the longer the delay the more people will just get an error trying to save.
> those privacy preferences being easily seen and changed in one place
We document every single network request that Zotero makes. Expecting them to all be configurable in one place in the software just isn't reasonable. Normal users think of features, not HTTP requests, and auto-sync doesn't have anything to do with translator update checks.
> I'd be fine with "we have limited resources; know privacy is important; are improving; know we have work to do to implement best practices, are working towards it".
OK, but I'm not saying that. I'm saying we consider privacy in all our decisions and believe we've made the right calls (and, for what it's worth, I can't recall a single complaint about our approach to privacy in many years). If you disagree with a specific decision, that's fine — come to the forums and we can discuss. But let's be clear about the features that would break for users as a result.