Friends aren't family. I never actually said what we do in our house, I was just surprised. My children have sensory issues, and as such, they cannot stand underwear, so please don't assume everyone can easily be comfortable in underpants. My point was, I don't think many 3 year olds are ready to bathe, dress, and toilet alone yet, so it seems a bit young for them to always be covered even just around family. While many are saying total nudity is extreme, I think expecting a 3 year old to always be covered and take care of their bathroom needs alone is a bit extreme, but then all children develop differently. Also, it probably does depend on the region - in some states, such as Florida, family nudity is illegal, but it's more well-tolerated on the West Coast.I agree with Sharlla, 3yo is old enough to keep something over their bottoms. Heat shouldn't matter because you can be just as cool and comfy in under pants or a pull up as they could be in the nude.
Also why should it matter if the bathroom door is open or closed? Does your family make it a habit to keep it open regardless of what actions they're taking IN the bathroom, their state of undress, or the company in the house? That seems slightly awkward to me. I don't think I'd visit friends is they were pooping with the door open or other type of PERSONAL functions while they have guests over.
Just my two cents.