What is this all about?

Cycling through the city of Praha is often quite adventurous. Thanks to the car drivers.

Today I went behind a car driven by a woman. She went really slowly and I just wondered why. Then she suddenly turn to right to enter the garage. With no flasher – the basic communication instrument among the actors in traffic operations.
This is not the only incident. Oftentimes I have to think about what the driver in front of me will do. I just wonder why those car drivers are such untactful.