I’m going to speak to Politics & Elections & Great Debates with this. But it somewhat applies to Cafe Society also. This is my take and not a universal rule, though I think it is fairly consistent for the P&E/GD mod team.
The OP does not own their thread, but the more detail they put into the OP, generally the more we try to moderate to keep it on topic.
If an OP flags later posts, we are more likely to moderate then from a non-OP.
The other factor is often time. When a thread is very busy, we’re more likely to stop off-topic stuff, once a thread has died down, we’re more likely to tolerate it. There is a lot of non-black & white decision making that goes into this process.
Keep in mind that Omnibus threads are specifically forbidden in P&E & GD. So this also factors in. I believe that rule went in January 2020.
We are discussing aspects of the hijacking rule currently, @Aspenglow got a conversation going on this last night.
As to Cafe Society & In My Humble Opinion, we usually allow a lot more leeway in those. The how busy is a thread really comes into play for Cafe Society. If the conversation has really died down, then we’re more likely to allow diversions and also posters are far less likely to flag.
breaking-news we in theory allow the least leeway.
Miscellaneous and Personal Stuff I Must Share & The BBQ Pit hijacking is very rarely enforced and is for the most part allowed. These are free ranging discussions in most cases.
Your example is tricky as the OP has very little to it. I might have leaned towards allowing the Church voting place conversation as it was kind of on point as I’m not really sure what that OP as written was expecting to discuss. But I also see it as not really germane to the article linked. So I think that could have gone either way.
Hopefully this answers your questions.