The current suggestion network wide is that these situations should be covered by using the Close as Off-Topic with the Other option and using the description to describe why the question should be closed. This is then added as a comment to the question along with the vote.
The reason why the "too localized" reason did not make it into the current set of close reasons is apparently because it was one of the most widely abused and mis-used close reasons before the shake up. Although it was occasionally used correctly more often than not it wasn't and the result was misunderstanding, accusation of bias and recriminations.
So, with regard to your example 'localised questions', I would suggest the following reasons:
Where's the problem in my arduino code dump?
- This question appears to be off-topic because it is asking for someone to review and possibly debug your code. While tangentially about robotics it is mainly a programming question with such a narrow scope that it is unlikely to help future visitors to the site.
What's the fastest X?
- This question appears to be off-topic because it is asking for information which is likely to go out of date very quickly. While an answer may be relevant now, it is unlikely help future visitors to the site.
If we feel that this is a significant problem, we could consider adding Questions which are too localised to the Some kinds of questions aren't allowed here section of our
What topics can I ask about here? page in the help centre. Suggestions for this can be added to my answer on our What should our FAQ contain? meta question
We could also add it to our list of close reasons, but since we only have three of these and each 'too localised' close is likely to be for a different reason, I think that sticking with Close > Off-Topic > Other is fine for now.