Those taggers should find an alternative hobby, such as learning how to Photoshop (or a similar image manipulation software). A good tablet (such as a drawing tablet like Wacom or Huion or a tablet computer like iPad or Surface) will help.
This way, they can tag structures without vandalizing them in real life and share their artwork with others. This would allow taggers to express themselves freely without damaging the property of others (including public property), especially without the permission of the property owners (including governments).
@kotsy does an amazing job at this. He shares his photos tagged with his name here on UT without any real-life property damage.