If turbotax knows the tax withheld from my 1099R(s), shouldn't the program also ask about income on 1099R(s)?

The only way that the program knows how much was withheld is what you reported when you reported your 1099-R and income is known the same way. 

Did the 1099R withholding show up on 1040 line 25b?   Then you must have entered the 1099R.  Does the gross amount from 1099R box 1 show up on line 4a or 5a?  Line 4 is for IRA and line 5 is for pensions and 401ks.  Did a 1099R show up on the wrong line?  If it was on the wrong line the IRS missed it and says you didn't report it.    Or was the wrong taxable amount listed on 4b or 5b?  

TurboTax does prompt you to enter the income on the 1099-R, on the same screen where you enter the tax withheld. In your earlier post about the same situation you said "The amount was not entered." If you did not enter the income, that is not something that TurboTax is responsible for. The boxes for the income are at the top of the same screen where you entered the tax withheld.

Either you did not enter the income, as you said, or you entered something incorrectly or in the wrong place, or you answered a question incorrectly in one of the screens after you entered the 1099-R. All of that input is your responsibility.

Please keep all your related questions in one thread. Do not post separate questions about the same issue. When information is scattered in multiple threads it's confusing and hard to follow, and hard to see the whole picture. If you have further questions, please reply in this thread. Do not add to the other thread, and do not post any more separate questions about your 1099-R income.