Is it? Superstore chain (let's say Walmart's) cost/benefit margins of coloring the walls is orders of magnitude larger day to day, than ad revenue budgets of most companies year over year. People like to be outraged about the most fringe issues, because they feel like it's championing the good fight. Advertising is the least of life's problems (local or at large). It's fucking 2020, can we get Pepsi and Coke in the same restaurant yet? That's an advertising issue that I wish someone would address.

That's because Walmart is gigantic, not because blue vs green walls make such an enormous difference.

It's the difference between having some vapid happy tunes playing in the super market and them analyzing your profile and previous purchases to bombard you with customized messages to make you feel bad because you'll buy more. The level of invasiveness is very different, and you need thorough tracking and denial of privacy for one but not the other.