About cost. The model of Personal Locator Beacon I own costs $270 US (the price has dropped $30 in the past 3 years) and weighs 5.4 oz. (about 128 g). Its battery lasts 5 years. I doubt that a drone could be that cheap, or that light, even if it were legal.
Many people (I'm not one of them) prefer a gadget (SPOT or Inreach) that will send daily reassuring messages to the family back home. I doubt a drone could do that even if it were legal.
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey