just come back from yilan, it is difficult to get a taxi except from train station. I asked the 旅館 to help to call the taxi and it is fine.
But at some rural spot, it is more convenient if you 包車 as you have to wait for the taxi to arrive after you called them. It normally takes around 15-20 mins. And may be more expensive because the taxi will charge you higher because they will charge you assuming you started the car from the city. I note that there may be a normal rate/standard rate for 包車 (ie around TWD3000 for 8 hours per day within yilan and all the nearby) because all the taxi offer the same rate to us.
At the end, I did not 包車 as I did not go to a lot of spots within one day. So the overall taxi cost is less than TWD 3000 a day.
Or if you booked a 民宿, you can ask them to give you the taxi contact, the taxi will give you a quote after you state the spots of visit which affect time on using their taxi service.
next time if I go there again, we shall rent a car. It should be cheaper and more convenient. My friend also rent car in the past. But I shall recommend to take the public transport from taipei to yilan as it is easy and able to save cost.