YouBike is the correct first move. Stations are dense in Taipei and getting denser in New Taipei and Taoyuan. The river paths are real. For a year of errands that stay in the basin, a card and a helmet habit will take you farther than a scooter you are afraid to park.
The argument starts when rain, a hill, or a child enters the week. Then an e-moped is not a personality. It is how you get a wet four-year-old from kindergarten to the supermarket without turning the afternoon into a story. The costs that surprise people are not the vehicle. They are the license, compulsory insurance, and the fact that the sidewalk is not a space.
If you are going to take the test, take it in the first three months. People who wait until they “really need it” spend a year in the back of Ubers they resent. People who buy the scooter first and study later park it under a tarp and keep riding YouBike anyway.
Try both before you join a side. A month of YouBike in your actual neighborhood — not a Sunday on the left-bank path — will tell you if the hill is theoretical. If it is not, go get the license. We have a separate note this week on the one you brought from home, and the one Taiwan actually wants.