The title seems to ask "why was another user's question left open" while it looks in the body more like "why were my similar questions closed"?
Why a specific question is left open is often hard to understand, fathom or explain. It is often easier to try and retrace the reasons why a specific question was closed. That there might exist some discrepancy in 'equal treatment' of similar questions could be one problem we need to try to address, as is the tendency of growing reluctance to either close or further improve – that is sometimes: change – a question once it has received an answer or even several of those. If that is the primary purpose of this meta question, then I would simply agree with you: that the 'left open' example should have been closed as well, and certainly that it should not have been allowed onto the hot network question list nor stay there for as long as it did.
However, since I participated in no actions either way on the listed questions, I can only offer what I think is the more important aspect for this meta-post: 'why were my questions closed?'
In this case it seems to be further a question of 'why are my movie inspired questions closed?'
That movies seldom are and really often cannot be historically fully accurate should come at no surprise. That some look more like it and some even claim to be closer to 'the truth' is another matter. Very often they invent scenes, dialogue, dramatise events and mess with chronology. Artistic license and entertainment value always trump historical accuracy. But that just means that the informational value of 'movies' is generally very low.
The examples of questions you posted yourself which were closed were all 'inspired by movies'. That in itself is fine – with me. (And in several aspects also OK with other Meta users: Can movies be considered usable for reference?)
Inspiration can come from anywhere, even random everyday musings or observations. Your questions were even positively identifying the movie with name and stills and links to an accessible platform. That is a plus.
But the problems I would have had with those questions:
- Personally, I would have been disinterested in both the inspiration and the topic. Perhaps other users would be interested, I'd simply not vote in any way for that.
- In each case it isn't really clear to me whether the questions were about 'the history' or 'the movie'. Or: is HistorySE really the ideal place for that question? A point that would need 'fixing' and it would probably be accomplished by addressing the following point:
- I would have been dismayed for that they all lacked any indication of you trying to solve the problem yourself. In other words: no prior research evident. This would have been prompting me to vote down and to vote to close as well.
This is illustrated by a comment that said:
As far as I can see, your question about HumVees was answered by the Wikipedia page on the HumVee (per my comment on the question). Irrespective of the inspiration behind it, that particular question was therefore off-topic for being 'too basic' (as explained in our Help Centre). – sempaiscuba♦
That looks to me like there are now some options for further action:
- Clarify this meta question as to whether it is more about sub-standard question being left open or your own questions being closed.
- If you just do not like the 'open question' to remain open: vote to close that question.
- If you want your own questions to be undeleted, try to edit them into a format that makes them on-topic. One aspect I'd require would be that they should show more prior research. Then flag them for undeletion review.
- If you want to ask more 'movie inspired' questions, then go ahead, and make sure you do not post your question immediately after watching the movie, but after you tried to solve your puzzle yourself. Document your research in the question post. Depending on far you get, you then might even post your own answer to your question.
If points 3 and 4 are the main focus here, for moving forward perhaps also revisit more posts on 'question quality' here on meta.