If you ignore the meaning assigned to it in everyday English and concentrate on the mathematical sense, it leads to absurdities as practically all physical objects can be described in terms of fractions as they include improper fractions, irrational and complex numbers in the nominator or denominator etc.

"A fraction of the price" means "significantly less". When someone promises to sell you a new Macbook for a fraction of the price but it turns out the price difference is 5 cents, from your point of view they're correct but you have every right to feel cheated.