When People Eat Loudly

When I was young, I was taught it was rude to make a lot of noise when eating and to not slurp your food. So why is every food court filled with the noise of wet chomp noises? Normally you shouldn’t be able to hear someone chew, so why is it I can hear you from 20 yards away? Close your mouth! I hate being able to tell what you’re eating from the noise you’re making.