You cannot lobby the government to impose a tax on a particular entity because you think they should be paying tax. Their liability to pay tax is dictated by the relevant legislation. As such, you need to identify the specific provisions in the legislation that are flawed, or loopholes that need to be amended.
If you believe there has been a breach of the Income Tas Assessment Act or the A New Tax System (Goods and Services Tax) Act or other tax legislation, contact the ATO with the relevant sections of the Act that eBay are in breach of and report them. This can be done in writing, via the phone or online via their website.
Bear in mind you cannot legislate to impose tax specifically on ebay alone. The ramifications of amending the Act(s) is that the amendments may impose tax on other foreign entities not currently liable to pay tax. Similarly, when other countries modify their legislation as a result, tax liability may then be imposed on Australian companies (including Australian sellers on ebay that sell worldwide). Jurisdictional provisions must be clearly defined to avoid the situation where entities are paying no tax in any country, or conversely being liable to pay tax for the same transaction in multiple countries. Australia needs to work with other countries to ensure legislation is consistent with regards to jurisdictional provisions.
Prior to any legislative amendment an assessment needs to be made in terms of the impact on tax revenue, and the flow on impact to the economy.
