What do you think of the practice that many commercial places that provide food are not allowed to bring their own drinks?

I think it is because merchants have set such a rule for their own profits that they are not allowed to bring their own drinks in commercial places that provide food, because many times, merchants rely on products such as drinks to drive their own profits. If a restaurant wins by dishes, it will not set such a rule, because for them, the operating profit is enough, so there is no need to limit the profit of drinks.

I once met such a hotel when I was working part-time. Because this hotel had just opened at that time and was not particularly familiar with some regulations, it blindly followed other hotels and set up this slogan, which really increased a large part of the turnover at that time.