Your comment uses the word 'margin' in two different senses, which makes it hard to evaluate its claims.
When you talk about 'beverage margins' or 'food margins', you must be talking about 'gross margin', i.e. [selling price, less direct costs of good sold] / [selling price]
When you talk about 'restaurant margins' and mention 2-6%, you must be talking about net profit margin (i.e. profit as a percentage of revenue).
It seems like you're comparing gross margin on beverages, with net margin for a restaurant overall. Not apples to apples.
The markup on food (based on ingredients only) and wine is similar (3x). It costs virtually nothing to store wine or to prepare it for sale. But the process to take ingredients and make a meal takes a lot of labour and machines.