This is because the Austrian capital has a parking permit system that covers the whole city, meaning that if you want to park your car on a public street, you will have to pay. Short-term parking zones and residents' parking permits are valid in Vienna's districts, meaning that in the entire city, parking a car is only possible with either a resident's parking permit (Parkpickerl) or a ticket (Parkschein) for the short-term zones. If you park your car outside your district (or don't have a Parkpickerl), then you need a specific ticket to park your vehicle on almost all Vienna streets.