There's a saying in economics that "in a perfectly competitive market, nobody is making a profit - because if they are, someone is losing customers". In a perfe

There's a saying in economics that "in a perfectly competitive market, nobody is making a profit - because if they are, someone is losing customers". In a perfectly competitive market, everyone lowers prices to the point they can't lower them anymore, and that tends to be the same price for all competitors. In a market where someone is making billions in profit, it's almost de-facto evidence of a lack of competition. Not a priori, obviously, but it gives you a basis for measurement that where you're looking is somewhere on that spectrum. For big box stores, that razor thin margin is exactly what you would expect from a very competitive market and so it's fair to say that it is one. Who else can charge 30% on every sale just because?