One that doesn't have any dark patterns and caters to 80% of common requirements majority of the population has. The proprietary software can still cater to the remaining 20% of cases which can be arguably complex.
I'm sure there's tax rules that are constantly changing and keeping up with them is difficult, but I'd imagine this is where social coding such as GitHub etc... would flex its strength.
How would one go about structuring a project like this without it being torpedoed by the current incumbents who arguably wouldn't want something like this to become mainstream.
An open source tax software would have to do the same updates to compete with Turbo Tax and others.
The IRS has a free to file form and Turbo Tax online has a free to file IRS and state for college students and people who take the standard deduction.
I want to write business software for Linux and MacOS so that Windows does not have the monopoly on business software. When I mean business I don't mean media creation tools or Excel but accounting programs that can manage a business and finance it.