> except we don't have the expertise to judge their performance.

Well, this is a bit different in that regard. Last time I tried it, it was free to put all my info into turbo tax and see what my amount owed would be, and then it would be a fee to actually file. I assume most tax software works that way.

So it's actually very easy and objective to see the performance of these systems. It would obviously be a big hassle though to spend a whole afternoon playing with all the different tax softwares.

I can assure you the secret sauce in "exploiting" tax law is almost never in choosing one thing or another during filing (there should only be one optimal answer once the facts are already created), but in tax planning. The tax software even hints at that. Paying for tax filing itself is basically a low-level scam.

Tax filing is very complicated and ridden with risk if you don't check the right boxes.

"there should only be one optimal answer once the facts are already created"

Yes, there should be. The reason why accountants can make a living filing taxes for fee is because that optimal answer is often difficult to find.

"Paying for tax filing itself is basically a low-level scam."

Not for me it isn't. If a private company can create a service that makes filing a lot easier and safer, I will gladly pay the fee.