However for startups, the tax system can work very well for you if you make full use of it. The recent changes to the R&D Tax Incentive have made it very popular with startups as it can fund up to 45% of the development costs. Every year I see many five and six figure tax refund cheques go to software startups that don't have significantly large revenue.
Once you get larger, the tax & other benefits of offshoring are undeniable. I would expect that Atlassian will keep their development teams in Silicon Valley and Australia, who can still benefit from the better access to capital and valuations from outside of Australia.