Personal filing is always free, the "free" in "free filing" refers to the prep part. It just means you fill out and submit your taxes yourself rather than paying a tax firm's accountants to do it for you. Calling it that makes it seem like the firms are part of the process rather than bloated parasites feeding off taxpayers. I wouldn't be surprised if the name was also a result of their influence.

Their accountants can claim exemptions and rebates buried in the tax code that laymen wouldn't know exist - ones that they lobbied for to make their services more attractive. It makes them worthwhile for some households, but only because they're solving a problem they birthed and grew in the first place.