Ponies React a lot better to alcohol than humans.
A ponies Magic will protect them from most detrimental effects of Alcohol. A Drunk pony won't behave like a Drunk human. They will instead behave like a drunk cartoon character, acting funny, being stupid and making silly decisions and getting married, but won't turn dangerously violent or sustain long term damage. They also won't pass out and choke on their own vomit. They will just go to sleep when they reach a certain threshold. Before that threshold they will become more and more hyper and silly and prone to shenanigans. Luna could make Moonshine because she held the Element of Laughter
In the future total alcohol content of a volume of Drink will be measured in Pinkie Pies."This Barrel of special Cider, My Little Pony, contains seventeen Pinkie Pies of Liquid Laughter. It won't go bad because a rotten barrel of cider would be sad."- Liquid Laughter is a dreadful poison, that works only on Common Sense.
