Since the project is long term, 20$ - 30$ per hour comes to around $41k - $61k per year. This is a pretty good amount in the vast majority of the countries. The target audience is obviously not developers living in Silicon Valley. Probably looking for developers from Eastern Europe, Asia, Africa or South America. Also, there are a lot of countries that offer tax benefits when you are working as a freelancer.
In some countries say like India, a freelancer can register as a one person business/one person company and all income treated as business income. This way your tax payable becomes based on income-business expenses similar to an LLC or corp.
In my experience, taxes in US are not lower if you include health insurance premiums and out of pocket healthcare costs.
The US is great if you’re in top 10% of incomes, but if you can’t afford to take advantage of the money tax exemptions and credits, then it’s not any better for the middle 30% to 70% of income earners who don’t make enough for government assistance, but also don’t make enough to take advantage of the tax code.
As GP just said, this posting is probably not intended to be taken up by a US person. There are many markets around the world where that's a very good salary.
