Firstly, I don't think tippers NEED this info. Adding it would just clutter up the app/site, more clutter=people paying less attention to the content in front of them.
And you're still ignoring the fact that the minimum is there because Tapas has to pay fees to get that money to the creators even after paying the cut due to the app stores. Digital transactions are full of fees! It's how businesses can stay afloat providing the service to have digital transactions. There are fees through ko-fi, Patreon, even direct Paypal donations.
Spending money WOULD support the creator, the money would go to the app store, showing Tapas is a viable app/site and that this coin system works, it would go to Tapas, the site that hosts the creator's work, and then it would go to the creator after a while.