That loaf of bread you prefer is not the only brand on the shelf at the grocery store. Most are good quality products with similar pricing. But if one brand tries to raise its price much more than the others without a noticeable increase in quality, that brand would lose some of its sales volume.
It's called competition.
When Henry Ford first made the T-Model car, you could get it in black, black or black. As soon as a new car competitor introduced cars and you could choose a different color other than black, Ford started making cars in multiple colors. Now look at the colors, the styles, the sizes and the many other variations in car choices we have today.
It's called competition.