How to ensure you are getting a fair taxi fare when you get off a plane?

I recently traveled to Italy and made the mistake of using the taxi instead of the train like a normal person, and generally I’d like to know how to prevent this from happening again. <br><br>Our taxi driver told us 45€ for the initial ride. Liked 2 days later we used the same taxi service with the same driver and it was 50€. I understood that was what the fair was. Then we used the same taxi 2 more times and the initial price was between 75-80€. In the end it was over 100€ and we tried to protest saying that wasn’t what we paid last time and the driver became very aggressive. <br><br>Since I’m traveling so much it’s becoming a problem when these things happen. I’m not sure if generally I just suck at reading people or if I just travel too much. <br><br>Is there a way to 100% ensure you are getting a fair taxi price?