Why does it have to be cheap?

It doesn't have to be --- but you may be wasting your money if you run in "store mode".

As noted above, "store mode" will usually max out the brightness, saturation and contrast while removing user control. This looks pretty "normal" with cheaper models. More expensive ones can become overbearing.

It appears to me that in some cases, the difference between cheap and more expensive is mainly the color adjustments.

In order to take advantage of economies of scale, they may use the exact same screen panel on multiple different models but limit the cheaper ones in software so it doesn't look as "bright" and "eye catching" in the store as their more expensive "killer" model.