Seems those that bring you hair color in a box have gotten the message. You'll notice more fruity scents rather than something that smells like a toxic waste dump when using them. Apparently all part of an effort to make the time spent coloring your hair seem more like putting on make_up rather than doing something that requires you don a hazmat suit.
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.