Hair color isn't always about just "color". It's about shades, hues, and a good cut that will show off your new color. Perfect color doesn't come in a bottle. If you are hoping to get a color correction for past mistakes (caused either by you or another salon), it will take a real expert to add in the right toners to counter the faulty shades you are trying to get rid of.
That's not to say you're going to duplicate the salon experience at home any time soon exactly. But it also doesn't mean the over the bathroom sink approach can't be more enjoyable, or pleasant even, now does it?In other words we've come a long way, baby when it comes to coloring our hair.