[Taler] caps are about currency not coins

[Fabian Kirsch]

Hi

The whole capabilities feature is a currency feature. And therefor 
outside of talers implementation concern.

So as taler coins can reflect any currency on earth, i suggest to run a 
bank which has "$18+", "$21+" as well as "$" in their currency 
portfolio. And then any service may say "please id, or use $21+ coins". 
The bank knows their customers but not their spending behaviour. 
Europeans may choose "€", "€16+", "€18+".

For other caps like "$,food only" it is the bank that checks its 
merchants to be eligible. The service could advertise "we accept 
$-food-only". This allows questions like "does beer count as food" to be 
settled different in different parts of the world.


This also makes the whole topic a regional one, where cultural norms are 
more likely to find agreement whether they want the capabilty feature or 
not.

greetings Fabian