Australia with Japan are the only countries in the world which are doing legislation with blockchain and digital currencies.
In Australia since July 1st the Bitcoin has not double GST or tax. Anyway there is a public consultation during this month.
Also is possible they release their own digital coin soon. A ozzycoin.
¿how is this topic in other countries?

Public consultation on the exposure draft legislation and explanatory material will run for four weeks, closing on Wednesday 26 July 2017. The purpose of public consultation is to seek stakeholder views on the exposure draft legislation and explanatory material.

The Government has worked with industry to identify the best option to reform GST law to remove the double taxation. In May 2016 the Government released a discussion paper entitled ‘GST treatment of digital currency’ that outlined potential approaches to remove the double taxation of digital currency.

More info here:
https://www.treasury.gov.au/ConsultationsandReviews/Consultations/2017/GST-removing-the-double-taxation-of-digital-currency