Great service but a monthly fee?

I use Hyperdia for everything but I find it extravagant that this app has a MONTHLY fee. A one time fee would make sense and I would buy the app no problem but I dont see any point to pay for it every month when the website is free and works just as well as the app. $3 a month is by no means expensive but not necessary for this app. The service gets 4 stars from me but the app gets 2 because theres no point is paying for the app when I can just use the webpage.

Tea1234567890 about HYPERDIA by VOICE, v1.4.1