Because one tends to happen naturally… the other doesn`t xD . Plus natural tanning is not bad as long as you take care of yourself, in fact, it´s good for you (10-25min)
People just ignore or don't want to know how bad for their skin sunbathing actually is. As for bleaching, I don't really know what it entails but it doesn't sound like a healthy thing either
Are we talking socially or cosmetically? Socially bleaching is problematic because it basically shows an idolization of white-skin as being preferable to one's natural color. Tanning on the other hand is reflective of a natural process that darkens the skin and has become symbolic of one having a luxurious time with enough leisurely opportunities to get a sun-tan naturally, or that's the idea you're supposed to be wanting to pull off. I'm not sure what good messages there could be from someone wanting to look whiter, other than having issues with their skin colour and/or ethnicity.
Depends because there are different types of tanning that are unnatural. But essentially like everyone has said sun tanning for the most part is safe and happens naturally. Although really we shouldn't be concerned with what other people do to their skin.