As Amazon heads for a $1tn valuation, the company usually speaks softly and carries a big stick. Chief executive Jeff Bezos, the world’s richest man, has remained mostly silent as Donald Trump has accused his company of everything from tax evasion to gutting the US postal service.

But criticism from progressives such as Bernie Sanders is another story. Last week, Mr Sanders said too many of the company’s workers are on public assistance, and he plans to introduce legislation to make big companies such as Amazon pay for offloading the cost of low wages to the state. Amazon fired back in a blog post, saying that the Vermont senator’s comments were “misleading”, and it encouraged employees to share their stories with him.

They should, because it would help open up the black box that is the online retailer. The company is approaching the first anniversary of its HQ2 search, a highly publicised but opaque bake off between cities seeking to host its second corporate headquarters. (Seattle, home to the first, cannot accommodate more growth, in part because housing prices have risen so much.)