It’s all about a physical HMI. The TFT-glass with its contrast, pixel resolution and viewing angles. The backlight behind generating enough brightness with reasonable heat. The touch-sensor with its x- and y scanlines being as transmissive and sensitive as possible. The cover glass giving surface protection but also reducing light reflections. And then finally the different bonding methods and materials binding the whole display together, at the right price and quality, available as many years as possible.