Hi all...
I'm suprised that everyone is shocked by this...
When SFII was new, it was hugely popular and a big money maker. I remember playing this on many converted arcade games in many locations.
I've seen the following converted to SFII back in the day, cause I played them!

Frogger
Defender
Centipede
Zaxxon... which many were also Ghosts N Goblins in the '80 too.
You have to remember that in the beginning of the '90s that "classic" arcade games were at the time still considered junk, and lucky to be still around, so arcade and route operators repurposed them with converstion kits to make money..... and boy did they!