I’ve just voted to re-open one of those questions, now that it satisfies the requirements of the single-word-requests tag for context and examples.
Questions are put on hold when they are either off-topic as defined in the Help pages, or unanswerable for another reason. Many tag descriptions provide quite a bit of help on the sort of question they are to be used on (and, occasionally, not to be used on), including how to frame the question so that it can be answered.
If a question is put on hold because it doesn’t contain the detail it needs, it can be edited to fit what’s required; you did that. Then it needs to be reopened. There are a number of ways to achieve that: I’ve listed some below in order of preference.
Editing bumps the question on the front page, which should get it noticed. Members of the community with the right privileges can then vote to re-open it. Your question had three re-open votes by the time I got to it.
You can bring it to the attention of the community by asking a question on Meta. Including a link is necessary; it’s also very helpful to summarise the changes you made to make the question on-topic (although these are available via the edit history).
If there are comments from close-voters, you can add a comment answering their concerns. If they are satisfied with the edit, they might vote to re-open. Some users don’t like receiving this sort of ping.
If the question was summarily closed by a moderator, then you could flag it yourself for moderator attention, filling in the “Other” reason as appropriate. This carries a risk that your flag might be declined, but a successful flag counts towards a badge.
All of this may take some time. Bear in mind that the users who voted to close your question may not be in your timezone. Generally it’s worth waiting at least 24 hours.
Deletion should really be a last resort, and the system doesn’t make it particularly easy. You won’t be able to delete the taxi question because it has an upvoted answer — but since the question also has upvotes, you may not actually want to do that. While question quality is not an issue here as they are both upvoted, deleted questions are not ignored when the system assesses a user’s overall ability to ask good questions.
The boasting question was improved by including examples, following the checklist at the end of the tag wiki.
The taxi question might be improved by adding research into the difference between fraud and scam, not taxi fraud and taxi scam. We value research!—and a well-researched question will often get a very good answer.
You will probably find that fraud tends to be widespread or systematic, or defrauding the government; while scams tend to be perpetrated by individuals on individuals. But as well as degree it's a matter of register: fraud is more formal than scam. You may need to consult two or three dictionaries.
Then edit that research into the question, together with at least one concrete example of the type of behaviour you are attempting to classify (including how widespread it is) and how and where you want to use the term — because the level of formality may be important.
The question may still be held as opinion-based, although I would say that such an edit makes it far more answerable; or you may find that your research actually answers the question you had. In that case, you could still edit the question but also answer it yourself.