When has “I’ll never shop here again!” ever been a useful threat? Shops care about people in aggregate, not you in particular. And anyone they decide to bother is someone they already have decided they don’t care about the opinion of.
Can you name a few, or even one, consumer-level boycott in, say, the last 50 years, which actually accomplished its goal? Accomplished by the actual boycott alone, I mean.
Walmart is a much higher bar geopolitically, but bet they have to jump too when word gets out of malfeasance. But it is a prisoner's dilemma when they are the main one-stop value shop.