Why is a 1099R from an annuity showing as an IRA distribution on my sample 1040?

You must not have checked the little IRA box between boxes 7&8 on the 1099R.  Is is checked on your form?

Oh I had that backwards.   But an Annuity can be in an IRA.  Is the little IRA box checked on your form?

If it's an IRA annuity (IRA/SEP/SIMPLE box marked on the form provided by the payer), it follows all of the IRA rules, including being reportable on Form 1040 line 4b (not 5b).