Is it normal that some studios draw anime girls without bras so their nipples are visible? This happens mostly with hentai and ecchi, but I've seen some that aren't any of those but still do this. I don't remember any girls in the streets going out without a bra at least in my real virgin life
I've had multiple partners who hate wearing bras and try to avoid it when possible. But they generally wear something thicker to hide it if they're going out. I've also had partners who prefer to wear them all the time even when relaxing. Bodies are different and weird.
I can only speak from someone living the West Coast of the United States. During the summer, it's probably about 1/3rd of girls are braless. That number varies by age group of course. But most people don't care and plenty partake in the "free the nipple movement".
Here in Greece where the weather gets hot as fuck in the summer, and where we get an incredible number of tourists, it's not uncommon to see some of them (one every two days for example, if you work around the busier places in the centre of the tourist city I live in) be braless.
Mostly younger (white, probably middle class) women, but I think people are slowly being liberated again with younger adult Gen z, after a big sexual closing-off that happened last couple decades.