A pub must serve drink. It doesn't need to serve food.

In Ireland that distinction matters. It generally will affect other things, like what time and how loud music will be played, how the tables and chairs will be organised and what type. It will often affect opening hours and the price of a pint. Gastro pubs also tend to be much larger.

In North America it seems the vast majority of "pubs" are gastro pubs, possibly why that lady couldn't see the difference. I personally love micropubs and they never serve food other than crisps and maybe a toastie.

I feel like a pedant but I get that dude in his 20s and had to speak up.

> In North America it seems the vast majority of "pubs" are gastro pubs

To be fair, at least in the US, anything calling itself a "pub" is already going down a marketing/branding road and it almost certainly means they're going to try to evoke an Irish or British sensibility.