Current pricing (until March 1) is $39 for TurboTax Deluxe and $69 for TurboTax Premier Online. I'd think that your son who paid $39 was able to complete his return using TurboTax Deluxe. That's the only explanation for the situation you've described.
I'm linking you to the TurboTax homepage where you can see current (discounted) pricing.
File Your Own Taxes Online | TurboTax® Official (intuit.com)
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
