We currently have the following tags:
Keep us-visa-waiver-program. It is specific and frequent enough.
Either synonymise or delete vwp. Synonymise if there is no other relevant visa waiver programme. Delete if at least one other country of similar relevancy here has one. Maybe also blacklist.
Tags are supposed to ease searching and categorise questions. At the same time, tags are not supposed to be inherently hierarchical, but sub-tags are allowed for sufficiently relevant sub-topics.
The us-visa-waiver-program fulfils the condition of being a sufficiently relevant sub-topic to warrant its own tag in my humble opinion. It applies to a very large country that counts lots of international tourists, a sufficient number of nationals are eligible for it and both sides are very likely to frequent Travel.SE. Indeed, it has sparked so many questions (174 excluding Closed as of right now) and sufficient answers to have a tag badge. Its name is good since it’s descriptive and non-ambiguous.
vwp is not a good name for a tag as it is potentially ambiguous. As of its current tag wiki, it is meant to mean the same thing as us-visa-waiver-program. However, the abbreviation’s full name is short enough to be allowed as a tag so that should be used to prevent mistaggings, misconceptions and misunderstandings.
I am unaware of any other sufficiently important countries that have a similar programme as the US do with their Visa Waiver Program. Thus, in its current state it seems like synonymising is the course of action to be taken. It is, however, very possible that I am just not knowledgeable enough and that other countries do have a similar yet distinct programme under the same name. If that is the case, then deleting and blacklisting the tag is the better solution, since keeping it could again allow mistaggings.
‘Sufficiently important’ is purposefully arbitrary. The UK is a rather small country but they are well-known on a global level and attract a high number of tourists each year. If the UK adopts such a programme, giving it a corresponding tag will be the correct choice of action in the long run. Papua New Guinea is twice the size but has a significantly smaller population and significantly less tourism. If they adopt such a programme we likely won’t realise for quite some time and a separate tag is not necessary. The extensive grey area in-between is where judgement will have to be used.
Finally, why would we want other country-vwp tags for sufficiently important countries? It’s basically the same argument as above; if something sparks enough questions (and the US Visa Waiver Program certainly does) then it warrants a tag.