tl;dr: AI-generated event posters look identical because people accept ChatGPT's default "craft fair" aesthetic; asking it to pick a deliberately different style, or naming a specific one (Bauhaus, Risograph, Memphis, Japanese minimal, punk fanzine, etc.), produces far more distinctive results. The author demonstrates this with a series of examples and notes ChatGPT will happily suggest style options if you ask. Tools like Claude and Gemini can also output editable HTML/PDF rather than flat images.