That and die wear lines making it appear as a mint mark, when it wasn't.
How did they prove it? By looking at earlier die states. They area in question was not there on them. Developed later, so it wasn't an over mint mark.
http://doubleddie.com/921576.htmlWexler still lists the 1981-D
Quote:
1981-D 1¢ WDMM-001
Description: An apparent S mint mark can be found north of the D mint mark.
Die Markers: Obverse: Die scratch from inside lower right G of GOD NW into the field. Reverse: Die gouge on upper side of slanted bar of N in CENT almost to junction of right vertical bar. Die gouge in field east of center of T in CENT.
Submitted By: Brian Allen
Cross References: None known
Comments: In view of the debunking of 1980-D 1¢ WDMM-001, it is likely that more study will go into this variety to make sure it does have an S mint mark and not a form of die damage like that seen on the debunked 1980-D variety. An early die state will be needed for such a study.
But as the last paragraph mentions it is still under study.
Edited by coop
07/14/2018 4:00 pm