Software tools are not really tools like a knife. They are more like cooking recipes.

Traditionally, people don't pay for cooking recipes, they may pay for cookbooks, that is a nice packaging around the recipes, or they may keep their recipes secret. Cooking recipes are like the software tools of chefs.

The actual tools of developers are computers, which they pay for, like chefs pay for their knives.

Software tools, like recipes cost nothing to copy and distribute, while actual tools, like knives and computers cost money per unit to produce.