Actually I believe it's a function that older machines were specifically designed to be either unwinnable (I've seen some old slots, certain ones don't have BAR

Actually I believe it's a function that older machines were specifically designed to be either unwinnable (I've seen some old slots, certain ones don't have BAR or 7 on all wheels) or for the odds to be exponentially against you. When the laws changed and gaming was regulated casinos wanted to make sure they weren't the ones now being cheated.