Why Can't They Improve The Simplest Things?

I use three kinds of brushes when I'm painting: sable, hog's hair, and the old, reliable nylon. After a day's work these brushes are cleaned with turpentine (some painters I know use paint thinner) and then washed with soap and water. They are used again the following day--hours of laying paint in layers on the canvas--and on succeeding days until the painting is finished, which takes months, even years.

My brushes have been used on hundreds of paintings, and they are still good. I only infrequently need to replace them.

Why can't the same durability be applied to toothbrushes? They are used only with toothpaste, not strong substances such as oil paint, linseed oil, turpentine, and paint thinner, yet, they last only two weeks before the fibers splay and get ragged. Hotel toothbrushes are even worse, because they are good for one use only and their handles snap with pressure.

Are toothbrushes one of the biggest commercial scams in this world? No matter what the brand, I don't seem to get what I pay for.