Are you sure the VHS isn't open matte? I did an A/B with the LD the first time Batman was shown on broadcast tv, and there was more picture information top and bottom.

Also worth mentioning Batman was one of the first movies to hit video only a few months after it was in theaters, (and priced to sell) so they might have rushed the video transfer to crank out enough cassettes in time to meet holiday demand. The LD didn't come out until well into 1990, IIRC. I recall being frustrated it wasn't out by Christmas '89, as the VHS was being sold everywhere you looked. It even came out on Betamax.

Not the first time a studio made us poor Laserdisc fans wait longer for a blockbuster movie. ;)