They would lose sales if it were. People are sensitive when it comes to their taxes. And I imagine a good number of accountants use Turbotax in the back. There could be legal issues with them uploading clients’ tax information to a third party’s servers.
However, fraudsters will use DIY software like TurboTax but then charge for it, evading all the provisions of tax law that pertain to paid preparers. This is not as severe a problem as it was say five years ago, since IRS has instituted a number of security features to weed out the fraudsters who efile.
The IRS and industry vendors (including Intuit) have, under the label "Security Summit", implemented things such as collecting metadata (tracking the network address from where returns are filed, how long the return was open in the software, etc), stronger password requirements with MFA required to submit returns electronically, limiting the number of refunds paid to the same address or financial account, and optionally collecting driver's license info to confirm identity.[0] It seems to have been relatively successful, as the frequent complaints of ID theft (returns filed under someone else's name) have declined significantly as a result.
[0]https://www.irs.gov/newsroom/irs-announces-dirty-dozen-tax-s...
It's kind of like the difference between having an Oracle database server vs. having MS-Access on the desktop.
https://proconnect.intuit.com/lacerte/pricing-main/
Back in 1998:
FWIW TurboTax is eminently easy to pirate and crack to get state filing functionality. Network isolate the VM after you get the updates and state forms but before you start inputting data, and you can rest easy that no personal data is being exfiltrated. There's no need to support these regulatory capture parasites.
FWIW I'm a Linux user that runs most everything in VMs. Each year I create a new one for TurboTax, get the updates/stateforms, then disconnect and never reconnect it to the Internet. It's a little work, but can be done mindlessly while doing something else.
That's useless for tax software though, unless they are getting updated every tax year.
Not sure if this would have worked on a web version or not, but I was pretty happy to have this option available to me.
Last night while preparing my 2021 return I opened up the 2020 software with my old return to review what I had done in the prior year.