The couple in the article did not have cell phone coverage, so no mobile device map apps would have worked.
That's what makes true satellite based GPS units so great for remote RV travel when used carefully along with paper maps, like the outstanding Benchmark series of atlas maps.
Microsoft even offers free built-in map software for Windows 10 laptops that is updated automatically whenever the Internet is available, but is completely usable with no cell tower access because it's all stored right on the laptop. It's almost as good as Google Maps with zooming, search, flat or topo views, etc. ... but can be used stand-alone on a Windows 10 laptop.
We prefer to travel independent of cell towers. Even recent disasters have shown the vulnerability of cellular systems. For an eye opener read articles to see how, and how long, cell towers are powered when external electricity to them is cut off. It's too bad that satellite phones and their services are so expensive and it's too bad that Google Maps - as excellent as it is - doesn't have a stand-alone version for laptops once they are fitted with large enough built-in storage capacity.