The cynical streak in me would suggest that now is a popular time to criticize major tech organs for their relationship to news, and the Australian government is hoping to use that to funnel money from US companies to Australian ones.
So while this approach with news media is a strange one, I think there is an argument to be made for taxing things differently. Make Facebook/Google pay a fair tax in all countries they're active in. Then each country can decide how they want to use that, if a democratically elected government in Australia wants to subsidize news using taxes they should be able to do so.
So indeed there is no clear simple implementation strategy for this yet.