"nd has a reasonable expectation that, as a result of using their software, you will save more money because they will help you find deductions that you would've been hard pressed to find yourself."
That has a lot less to do with software and more with you knowing the allowed deductions.
Funny how I have no problem finding these deductions using the free sw provided by the government (in more than one country)
I understand this is strange, but it works because deductions are often balanced. For example, you filing a deduction for medical expenses signal a correspondent owing of taxes by the doctor/hospital, so you're helping with enforcing collections.
" Is their system going to be designed to help you get as many deductions as possible? Are they going to prompt you to deduct moving expenses"
More or less yes. There may be the case where the software is going to be completely useless (like Argentina), but then you just skip the sw and go for a tax consultant.
"If Intuit/et al help you save $5000 in taxes this year by helping you deduct"
If you really can save 5k you 1 - probably know it 2 - may get the help of a tax consultant
But most people don't have deductions and should just file the 'default' for free.