You're not alone in thinking that the war in the Yemen is under-reported. Medium ranked it as the top underreported stort of 2015 and even the normally reserved BBC described it thus:
...the war in Yemen must rank as one of the most under-reported in recent times, despite a few brave visits by intrepid journalists and film crews
It's always difficult to give a perfect answer to questions like this but we do have some factual sources to go on:
- Several journalists and institutes have done research into why the war in Yemen is under-reported and written about this. This includes identifying some specific facts.
- Other journalists have written first-hand accounts of limitations in modern reporting, identifying principles and trends, some of which apply to Yemen
Since May 2009 we observed a very bad evolution, with a lot of trials, with a lot of journalists in prison, a lot of journalists harassed and it is really the worst evolution of media freedom in the world
- It's extremely difficult for foriegn journalists to get in. As Columbia Journalism Review (CJR) put it in their excellent article Why almost no one’s covering the war in Yemen, which I've quoted from many times and which I recommend reading in full:
...journalists say the current conflagration has made reporting on the country more difficult than at any other time in memory. There are vanishingly few foreign journalists in Yemen as a result of the violence on the ground, access restrictions, and wavering commitment on the part of international news organizations
(we'll come back to the "wavering commitment" part)
At the moment, journalists have no reliable way into Yemen. The Saudi-dominated coalition has bombed the airport in Sanaa, leaving some journalists seeking other routes into the country. Some have attempted to broker passage on ships bringing aid to the country.
A crew from BBC television managed to enter the southern city of Aden briefly in April, but left soon thereafter, apparently due to security concerns. Other news organizations are covering the conflict from neighboring Saudi Arabia, or from Djibouti, Cairo, or Beirut.
- It's hard for those few journalists who are there to get news out. CJR again:
Yemeni journalists, meanwhile, face power outages for days at a time [and] the threat of food shortages
As former Yemen correspondent Adam Baron was quoted in the CJR article:
“It’s the simple fact that it’s literally almost impossible to get information in or out of that country because of the apocalyptic damage and strain to Yemen’s infrastructure.”
General problems in modern journalism that apply to Yemen
But the problem isn't just the difficulty - there's also a lack of will, or as CJR put it:
wavering commitment on the part of international news organizations
Even when journalists have risked everything to get stories out, or when citizens have used social media to tell the world what's happening, many media outlets do almost nothing with these reports.
Why is this? In 2008 experienced journalist Nick Davies published a book describing in detail the ways and reasons why modern newsrooms fail to properly report important stories, Flat Earth News, and some of the principles discussed are relevant to Yemen.
- Journalists like "safe" sources. If a journalist publishes a witness account of a Yemeni villager, and it turns out to be a fraud organised by the propaganda division of one of the factions, that journalist feels their reputation is at risk. If a journalist publishes a statement by a Western government which turns out to be equally untrue, they get two stories for the price of one - the original statement, then the subsequent controversy about the misleading statement. So, journalists prefer "official" stories, since they feel their backs are covered, This is a problem for a conflict like Yemen where the actual fighting is done by factions in broad coalitions whose leaders simply don't comment on most incidents, and where finding impartial sources is difficult (CJR again):
the problem of finding sources in a polarized country where violence has hardened attitudes
- Modern journalists have little time to do original research or fact-checking, due largely to reduced budgets. This combined with the previous point leads to favouring "he said she said" stories, where they can simply copy a quote from a should-be-reliable source, publish it, and if other should-be-reliable sources dispute it, they quote them in a "controversy over X" piece. In Yemen, Western governments tend to not make statements since it's diplomatically awkward (Saudi Arabia is an ally). Human rights organisations do comment on events in the Yemen, but they are usually met with no response, so this isn't a good way to generate a cheap "he said she said" copy-and-paste controversy.
- It's complicated. Modern journalists are pressed for time due to understaffing due to reduced budgets, and favour easy pre-packaged stories that are easy to churn out (a trend dubbed "churnalism" by BBC reporter Waseem Zakir, popularised by Davies' book) over stories where they'll need to take time to properly understand and communicate something complex like the many agendas and loyalties of the many members of the two main military coalitions in the Yemen.
- There's no clear easy narrative. Publishers feel stories need a "hook", and for foreign wars this usually means turning it into a "good guys vs bad guys" story where the "good guys" are in some way "like us" or "on our side". For example, the war in Syria was a major story while it could be characterised as the "good" pro-democracy activists and Free Syrian Army vs the "bad" dictator Assad. It then slipped in prominence as many of the anti-Assad forces proved to be even worse than Assad's regime, then roared back into prominence when it could be characterised as the "bad" ISIS vs the "good" Peshmerga and Yarzidi. Neither of the two main military factions in Yemen is easy to characterise as the "good guys", so many news outlets simply don't know how to give the story a hook - and don't try.
Of course, there is a "good guys" faction who should be represented. As Yemeni-Scottish filmmaker Sara Ishaq was quoted in the CJR article:
“We’re trying to represent this third party that isn’t really being represented, and it’s mainly the civilians who are neither pro-Houthi/Saleh nor pro-Saudi.”
...but as previously discussed, modern churnalists don't see ordinary civilians as the kind of source where, if it turns out to be incorrect, the churnalist can cover their backs by turning it into a "he said she said" copy-and-paste controversy. So, they go unrepresented.