Oh god, I saw an old person naked. How will I ever live with myself?
What has been seen cannot be unseen.
Although written humorously, this is completely true. The images in my head cannot be erased. We don't have a delete button (at least, one not involving trauma). For that reason, we make rules such that people can avoid scenes they do not wish to have in their heads.
That includes Helen there.
However, discussing nudity is rather far afield, but it illustrates the gulf between our thinking. You think imposing nudity upon others is fine, as you claim there is no externality at all from viewing nudity.
If you believe that, then there is no way you can understand a locality's desire to ban other rude forms of dress.