Yes, both buses and dolmuş vehicles are generally safe for tourists. Istanbul's public transportation is widely used by locals and visitors alike. The municipality operates buses and adheres to safety standards. As for dolmuş vehicles, they are a popular mode of transport for short-distance trips, especially in more local neighborhoods. While safety is generally not an issue, it's always a good idea to exercise caution, keep an eye on your belongings, and choose well-lit and populated stops.