They have not, however, made any attempt to get the app approved to serve that function.

Not necessary ... it's MY app. The problem with not having approved and sealed meters is that I don't know if you've screwed with it or not. I know driver hasn't screwed with my iPhone app.

It's not your app. It's Ubers app, installed on your phone.

How do you know Uber hasn't screwed with your app? And how does the driver know that you are not screwing him with a tampered app?

It's not only you and the driver that need mutual trust either, the tax administration also has to trust the app.

Which is a great argument to make, but you still have to make the argument. As I understand it, they have not attempted to do so.