Normal chewing results in brief intervals of contact between teeth. Under normal circumstances, your teeth should only contact for about 5 minutes each day. Slight amounts of wear over years of use is common, and bite edges can chip a little.
Sometimes teeth develop a flattened, worn appearance, even in young patients. X-rays may reveal unusually thin layers of enamel as if sandpaper has been drawn across the chewing surfaces of the teeth. A few minutes of chewing daily simply shouldn't erode the enamel so much.