In this link https://www.irs.gov/individuals/international-taxpayers/taxation-of-nonresident-aliens I find it is written only those whose income tax is not satisfied by withholding are required to file as per section A)2) however on some other answers here state we must file.Can any android developer or anyone well versed in this field tell me whether I must file if I am a Non-Resident Alien and my whole tax liability is withheld.No post answers properly.
Withholding by a company or an employer is just an estimate of their window into your financial picture. There is no guarantee that it is correct for your entire financial picture.
So based on your statement "having their total tax liability withheld", the only way to know this is to have completed all the applicable tax forms, and calculating that you owe nothing, and that the government owes you nothing.
The catch is that even if you calculate it as zero, the IRS might not calculate it as zero unless they see everything on your forms. So if in a year or two they think you should have filed, because they tried to match a 1099 to a submitted tax form, their computer will guess if you owe them money.
They will then try and track you down and require you to submit a return. How likely this is I have no idea. Of course If you continue to receive income from selling online one of those years you will have to submit a form, and they will link the old 1099s to your new form, and may peruse you all over again.