Software for correcting grammar, spelling and usage is still limited to particular types of typos and errors.
Despite improvements, they often reject perfectly acceptable phrasing and can actually introduce new – sometimes egregious – errors. An article in the Economist drives home the point, revisiting a popular brand of grammar software and finding it not only lacks technical accuracy, but that it also suggested clearly unacceptable substitutions.
Grammar software falls short of promises of perfection because it can’t yet conduct reasoning tasks the way a human being can.
Much of the commercial content produced with automated editing programs can’t distinguish fact from error, American English from British English, or the right word from a wrong one.
It’s realistic to expect that grammar software will improve over time. But don’t trust it with your reputation (or your printing budget) just yet.