Why do people only see what they want to see?

I live in a community with a large Hispanic population. If I go to my bank or my favorite supermarket, I'm as likely to hear Spanish as English. Because there is a demand for foods common to Mexican cuisine, my supermarket carries a lot of those type of foods. Consequently, many people, originally from Mexico shop there. My question is, why do people, mostly white Anglos, including some of my in-laws, say that they hate going into the store and hearing people speaking Spanish and watching a bunch of grubby Mexicans buying junk food with food stamps? That is not what I see because that is not the way it is. I see mostly ladies with clean young children, the little girls with ribbons in their hair. Yes, occasionally a little boy might kick a soccer ball in my direction. Good God young boys, and girls, are supposed to run and jump and kick an throw balls. Because I'm nosey, I look in their carts in the checkout line and I see fruits and vegetables. They normally pay with cash or credit cards. Why are there mostly young children? Because the older children are in school and the husbands are working so they don't need food stamps. Why don't the parents speak English? Because they have only been in the USA for a short time. Should you have a question, ask one of the children. It's quite humbling to have a small child act as a translator.