Rental Car Insurance in Jamaica I do not get it. This seems perfectly within scope.
Voting on TSE is effectively meaningless. For questions it is supposed to indicate whether researched, useful and clear (or unresearched, not useful or unclear) but is evidently much more arbitrary. We have 1,366 questions that are Closed (but not for being duplicates) with a positive score, some in the net 30s. These are definitely not useful (just clutter) and indicate that research has not even extended even to determination of what is on topic for this site. The clutter is not useful because though Closed they often still require maintenance (editing and retagging) if not to leave an even more unfavourable appearance and set a bad precedent for use of tags. These and a further 387 'non-duplicates' are questions that will never be rumba'd with the votes they have.
Posting a duplicate is also sign of lack of research (ie there is already an answer on TSE, let alone elsewhere on the net) and there are a further 1,169 of those with a positive score.
People are allowed to vote almost entirely how they wish, in confidence, and though someone asking enough questions may 'average out' (for example due to being chosen as a Hot Network Question) the arbitrary nature will mean some low or negative scores. For example this OP received 15 upvotes for What is “Sprinter” in the Netherlands? when the answer to that question was and is readily available by simply searching "sprinter netherlands" in Google (for me the entire first page, except for one entry for Dafne Schippers, a Dutch woman who was World Champion for the 200 m foot race in 2015).
Close votes are a little more demanding since a reason must be selected. In this case both of those who voted chose:
Questions on price-shopping for specific goods or services are off-topic as prices and availability change frequently in many locations. See: What is a shopping question?
I agree not appropriate - but at least vaguely in the right ball park (ie the question is about shopping for a specific service, just not one where price is at the core).
Possibly "too broad" may have been a factor. Wording such as I am under the impression that the situation in JA is such that no credit card will insure rental cars there. hints at a requirement for an answer to cover every credit card. "Is there a credit card that will insure rental cars in Jamaica" might have been a better choice.
Anyway, the question was posted 2 days ago, in such a time interval other questions have received 5 Close votes and then another 5 Reopen votes (possibly also further Close votes). Voting, whether +/- or to Close is not at all scientific on TSE. This question is in no way unusual.
So the answer to:
Why is Rental Car Insurance in Jamaica downvoted and off topic?
is really "that's just TSE".