An air fryer marked down from $149 to $110; a trampoline discounted by 10 per cent and a set of star-spangled kids’ pyjamas priced at $9 rather than $12: the red “rollback” signs were not hard to find this week at the Walmart Supercenter closest to the retailer’s headquarters in Bentonville, Arkansas.
A mile from the small town square where Sam Walton opened his five and dime store in 1950 and began building the world’s largest…