eli5: Why do slot machines have „[BAR] as a symbol?

bar bar slotThe BAR symbol is a ubiquitous sht on classic slot machines, often appearing alongside other iconic symbols such as cherries, melons, and sevens. Unlike its counterparts,Bar Bar Black Sheep is a 15 pay slot with 5 reels and 3 rows. Players can bet anywhere from $0.15 up to $150 per spin . The top payout in the slot comes from landing five