Trademark Rights are Limited
A trademark owner can stop other businesses that sell the same product or service from using a confusingly similar trademark in a way that is likely to cause customer confusion about the source of the goods or services. That’s it. That’s all the power a trademark owner has. If there is no confusion, then there is no infringement.
So for example, companies making different products can use identical trademarks, like GERBER for baby food and GERBER for knives. No one is likely to confuse baby food for knives, or vice versa, and so there is no infringement.