The thick walls did precede smartphones, but when I found out that Macy's tracks customers via in-store wifi, [1] I wondered if they might keep using thick walls in the future, to ensure that customers have to use the wifi.
I don't really think their marketing team is getting involved in determining the electromagnetic characteristics of the construction materials used in their locations, if much at all. And while Macy's does own a notable amount of property, much of their real estate is leased. And yet more of the property they own, they did not build. The reason that commercial construction from the 1980s interacts with your phone's signal is the same coincidental reason it will likely do the same in 2040: steel and masonry are good for large commercial buildings.
1: https://abcnews.go.com/Technology/retailers-tracking-shopper...