Why there are no odd size trousers like 27 or 29 or 31 or 33 etc?

There are companies like Guess jeans that use odd sizes and most companies that use waist size for women use odd numbers. Sizes like 2,4,6,8 are just like small, medium, and large not actual measurements. Companies have veered away from actual measurements as a marketing ploy to encouragement size conscience consumers to buy.