Could be as simple as preventing airflow past a potential opening in the tank which could otherwise create a siphon effect.
Must not have been a universal problem, even within the squadron.
Note below that 29 (Kepford's plane) has main tank tape but no wing tape while 34 (Freeman's plane) has wing tape but no main tank tape.
That being said, it is the purview of the skinner to portray, as best one can, the historical look of the plane and until provided first person anecdotals not to fret the whys. I kinda like the differences.