Why many Americans don't know proper English...

I'm from a foreign country and I have been in the USA for 9years. I met my husband in college, he is an amazing guy, smart and educated. But his family is a bunch of ignorant rednecks, rude and proud of their ignorance. All those words on the picture, they use wrong. All of them. Why? Why? 
"Only in 'Merica" 😒