Traditional retailers continue to feel the pinch. But Amazon and ecommerce aren't the only causes of their problems—socioeconomic factors are also coming into play.

Sears was the latest bastion of retail to release disappointing sales figures. The company reported revenues for fiscal 2017 totaled $4.38 billion, down 27.7% year over year. The retailer now operates 1,002 stores, down from 1,430 a year ago, and plans to close an additional 100 by April.

This is just one more example of the so-called retail apocalypse. But these downturns aren't happening to retailers across the board. Shrinking revenues and footprints are the result of economic forces that have been long in the making. 

According to US Census Bureau data analyzed in a new Deloitte report, "The Great Retail Bifurcation," there is some truth to thinking that the rich are getting richer and the poor are getting poorer. 

Between 2007 and 2016, high-income consumers (the 20% earning more than $100,000) experienced 4% growth of their disposable income, to 63% of total income. The disposable income of middle-income consumers (the 40% earning $50,000 to $100,000) remained flat, at 39%, while low-income consumers (the 40% earning less than $50,000) saw their disposable income dip 16% to -23%. 

This widening disparity in US incomes is having an effect on retail. Deloitte looked at revenue growth among different types of retailers over the past five years: "price-based" retailers, those that compete solely on price like discount and dollar stores; "premier" retailers, which offer exclusive products and experiences; and "balanced "retailers, those that focus on price and promotions and sell widely available merchandise. It found the higher-end stores experienced revenue growth of 81%, while revenues for discount stores grew 37%. By comparison, revenues at midrange stores grew only 2%.

This pattern of growth on the opposite ends of the spectrum also applied to store openings from 2015 to 2017. Price-based stores opened 263 locations during that time, while premier stores opened 109. Meanwhile, balanced stores closed 108.

Selecting a representative retailer from each of these tiers—Kate Spade & Co., Ross Stores and Macy's—eMarketer's Retail database shows that while Macy's had the largest total revenues and retail store sales for the latest fiscal year, its revenues decreased by 3.7%. 

Ross, an off-price store, saw its revenues grow by 7.8%, and specialty retailer Kate Spade posted slightly higher growth (11.2%). Not all retailers fit into neat tidy buckets, though. Some luxury retailers are struggling, and not all department stores—which fit into the middle category—are troubled.

Neil Tenzer, vice president of corporate strategy and customer insights at Abercrombie & Fitch, characterized the current state of the apparel sector as "bifurcated," but this assessment could easily apply to the retail industry as a whole. "There are two places to be in the market—you can be on the price-focused side or the innovative side," he said.