During the years I was eligible for this program, I used TurboTax for free through it and it worked fine. It was a basic version that didn’t support complex transactions such as capital gains but for most people making under 66k it would have worked fine.
Very interesting to see only 3% use it. It would probably work well for a lot more of those 70%.
The paper forms are also easy enough to do manually, but can’t be e-filed and so the refund comes slower.
Another reason might be that "automatically" filling in your details from uploaded / linked documents is often a paid feature. I uploaded a doc it asked for, it showed me the info, then when I opted for the free tier it cleared the data and made me type it in myself.
However, I noticed that it's back for the 2018 tax year. https://www.irs.gov/filing/free-file-do-your-federal-taxes-f...
It's very basic -- it's literally just a way to fill out and submit the paper forms electronically (though it does the "add lines 35 and 36"-type arithmetic for you.) But it's an option for you procrastinators who earned more than $66K last year.
Relatedly, Massachusetts used to run a free online "TurboTax" program for all. To file your taxes you went to a government website and answered the questions. Unfortunately, that program was canceled a year ago when they upgraded systems, and now the only way to e-file is via a paid preparer.