The ranking might look odd at first glance but if wanting to build a retail culture one must prepare the infrastructure.
I have seen this process at first hand in Finland and then more recently in Estonia.
Like Russia, neither country had much in the way of a retail culture but with increasing personal wealth comes increased disposable income. Basically, folks need places to efficiently spend money. Unlike the US or the UK, for example there was not much in the way of previous infrastructure upon which to develop. No strip malls (in the USA) or high streets (in the UK). This meant that shopping malls were built with no previous history of smaller scale development. The result was an apparent glut of large malls filled with good quality anchor tenants and lots of secondary tenants who had innovative portable shop display fittings to enable rapid exit from the mall at the right time. Over a period of several years the population grew into the shopping malls and the shop fittings became more permanent in nature.
So, right now, parts of Russia will have large amounts of shopping space per head of population or per unit income. These places will look empty for a while. In a few years the population and their wealth will grow into these units. This reminds me of a shopping centre near to me called Ulemiste. When built, about a decade ago, it was the largest development in Estonia, it seemed huge and empty, a temple to shopping. Then it became crowded and busy and needed expansion. A year ago the 'new' Ulemiste opened its doors - now more than twice the size it was before and busy from day one.
On the other hand, until some other economy comes along with a pattern of rapid development it is quite likely that shopping facilities for Russians in terms of area per unit population will remain higher than other, previously developed areas.
What might have confused readers is the choice of the word 'destination' in the web article. London, Paris and Milan are places that people travel great distances simply to go shopping. They are 'destinations' for shoppers. Samara, like Tartu or Helsinki is a place where the inhabitants go shopping.