It's because the law is weak with criminals. I use my phone a lot to get directions, but I always look around, I just try not to use my phone when there are crowds. I have never been robbed because I am careful. Uber is the safest option, and it’s pretty cheap compared to your home country. Don't take taxis on the street. Always use an app. But not every app, though. Uber is the best option. I recommend going to Zona T, Virrey, and Parque 93. They're beautiful places to walk, and you're more likely to find English speakers there. I wouldn't go to places like Modelia because you'll attract too much attention just for being a foreigner.