Re: [Taler] Taler Android UX

[Torsten Grote]

On 2020-04-09 15:25, Christian Grothoff wrote:
> That sounds a bit too much like a dark pattern for really strongly 
> forcing people onto our pre-selected exchange.

Well, there is a balance to be struck between promoting competition in
the exchange market and making the app easy to use.

For you the logical thing to do is of course to show exchange selection
at least for the first withdrawal, but for the ordinary user who doesn't
even know what an exchange is, this could very easily be the reason why
why don't perform the withdrawal, stop using and uninstall the app.
Since we won't integrate analytics into the wallet, we'll never now.

My suggestion was merely meant to make things as easy as possible for a
new user who is already overwhelmed by using a new application.

> Sure, having an audited/trusted exchange default pre-selected in
> that dialog can make sense so that the user only has to click on
> 'next'. But skipping it entirely and immediately going ToS without
> even giving a hint that there could be another choice seems fishy.

What you *could* do is show an onboarding dialog already the *first*
time the user withdraws and tell them what an exchange is (as this is
apparently required knowledge) and that they can change it here.

But I would really recommend not forcing exchange selection upon the
user. Maybe Belen also has an opinion here?

> However, the rounding loss 
> is largely theoretical: if the exchange offers denominations that
> are at or below the smallest unit you can wire-transfer (like 1
> cent), the rounding loss will always be zero and can be
> ignored/hidden. But an exchange could also only offer say 50 cent
> coins as the smallest unit, and then it would become "substantial".

Ah good to know. So I am seeing the rounding loss all the time only
because our test exchange offers few denominations.

Btw. is there a difference between a coin and a denominations?

> Refresh can be for change, but also when coins expire, or when 
> transactions are aborted due to network failures. So not just for 
> getting change, but _mostly_.

Good to know, so the coin expiration doesn't mean that they will be
lost, but that I (or my wallet) need to refresh them before they expire?

Having to pay for network failures doesn't sound good btw.

> So an exchange operator COULD decide to 
> only charge deposit fees to make the consumer never see any fees 
> explicitly.

That sounds sensible.

> However, then malicious consumers could do (pointless) 
> withdraw-refresh-refresh-refresh-refresh and basically try to 
> "bankrupt" the exchange operator that way.

I guess it would need a lot of malicious consumers to achieve that and
imagine that one could put other defenses against that in place.

> In summary: the costs are sometimes substantially different 
> (bandwidth, computation and storage), and it is also conceivable
> that an exchange or central bank may set fees for marketing or
> policy reasons that do not even match the costs.

Thanks a lot for explaining!

> Wire fees are charged per wire transfer. The merchant(s) specify how
>  often they want to be paid (hourly, daily, weekly, every 42h, 
> whatever), and that's how often the aggregation wire fee will be 
> charged.

So do these fees only affect merchants? Do we even need to show them in
a consumer wallet?

> Closing fees are ONLY charged to customers that create a reserve 
> (wire money to the exchange) but then never withdraw the coins.

Interesting. Should we maybe have little info buttons next to the fee
labels with these explanations?

> I suspect the WebExtensions wallet isn't even ToS-aware at all at 
> this point. Also the exchange can't "enforce" this, because it 
> doesn't get anything when the user accepts the ToS. The system
> design says the exchange must offer it, and wallets MUST collect the 
> 'acceptance' from the customer before proceeding.

Good to know. Thanks for explaining!

Kind Regards,
Torsten