PREFACE
The problem with using the Japanese phrase “shopping refugees” is that it is unknown outside of Japan. In fact, if we Google the phrase in quotation marks, Japanese websites are among the first results: The Japan Times, J-Stage, a website dedicated to science and technology information in Japan, and a paper written by three Japanese academians, entitled Web shopping support system for elderly people using WebRTC
If we search the expression refugee shoppers on Google News, we receive exactly three results, one of which is a false positive. It's worth citing these two excerpts to illustrate why the coined expression “shopping refugees” would be misunderstood.
But for the immigrant and refugee shoppers at the farm, cooking bitter melon and foods such as okra, mustard greens, long beans, and red roselle is second nature
… humanitarian funding means much-needed relief for refugee families but also a considerable boost for Djibouti's economy, with thousands of refugee shoppers buying food in local shops and markets.
Oxford Dictionaries define refugee as “someone who has been forced to leave their country in order to escape war, persecution, or natural disaster.”
Consequently, from a native speaker's point of view, the term "refugee" conjures up images of immigrants, of all different ages, fleeing from political or religious persecution and oppression, people in desperate need of shelter, and protection. Not the elderly who live in towns or regions where small grocery stores have been forced to close. So @user2922582's answer, which recommends adopting verbatim the Japanese phrase won't work unless the context is provided and/or its meaning explained. Likewise, the answer the disenfranchised, which was suggested by @Bread, fails to describe the social phenomenon in Japan unless its author preemptively explains its meaning.
There is no established English counterpart to “shopping refugees”
This is reinforced by the following scaremongering newspaper headlines, articles that describe the demise of retail shopping often due to the rise of online commerce. Journalists and editors tend to focus on the loss of profit and jobs in the retail sector, rather than its effect on the poor, the infirmed elderly, and the semi-invalid
- The retail apocalypse
- Streets without shops
- The death of brick-and-mortar
- Retail Meltdown
- Walmart Is Ruining America's Small Towns
- War of convenience
- High street gloom
On the socioeconomic front
- Barriers to food shopping for older people
- Food Shopping in Later Life
- Small towns fight to save grocery stores
The disappearance of the grocery store — more than an inconvenience to the elderly, the poor and those who don’t drive — speeds the plummet of home values and any other lingering retail activity.
I did find one American English expression that had some affinity with the Japanese one, it's not one I am familiar with, so I don't know how well-known it is among British English speakers but the term food desert is about the availability of grocery stores and supermarkets or lack thereof, especially, in rural areas.
More than 18 million people, including almost 5 million elderly, lived in a food desert in 2010. The U.S. Department of Agriculture (USDA) defines a food desert as a low-income area where many residents do not live close to a supermarket.
Residents of food deserts face many obstacles in consuming nutritious food, ranging from fewer local stores with healthy food, higher food prices at smaller local grocers, and the time and expense of travelling to a supermarket.
As a result, living in a food desert may not only affect the quality of one’s diet, but also the ability to purchase food and other necessities and the need for public food assistance programs.
Compared to other groups, elderly individuals may be particularly affected by food deserts: strong neighborhood ties encourage them to stay in a community even after businesses leave, fixed incomes make paying higher food prices difficult, and physical limitations limit travel.
The Impact of Food Deserts on Food Insufficiency and SNAP Participation among the Elderly by Katie Fitzpatrick, Assistant Professor of Economics at Seattle University
"Food desert" is also mentioned in The Kansas City Star
Two out of every five Kansas counties include a food desert, an area at least 10 miles from the nearest grocery.
Brief description
I would suggest that the OP explain to visitors coming to Japan that "shopping refugees" are basically
the elderly without means of transport who live in food deserts
I know it's not snappy–it's eleven words–but it is understandable.