A negative can record a lot more tonal range than you monitor or any photographic paper can display. When most scanners scan negative film, they try to squeeze all the tones into the result, which yields ugly results if you have strong highlights and high contrast in your scene. This is why straight RA4 printing normally works much better for these kinds of negs. The only chance you have with scanning is if you get a high end scan with 16 bit color depth per channel, then you can manually adjust the tonal range to your liking.