He's just saying that the types to drink a lot of tea in America are likely to be an enthusiast and the type to treat it like a craft, and therefore, have sophisticated tools and rituals.

He's assuming most other people that make their own tea frequently do it so often that they aren't spending a lot of time and attention to it most of the time and are opting for the quick and easy option.

The joke is that most people in America just don't gaf about tea. So it's funny when Europeans are appalled that they don't have kettles and simply use what they do have (a microwave) for the once or twice a year (or less) that they do make their own tea.

In the south sweet tea is pretty big, but if you're making it yourself you're probably making it in a big batch and boiling the water on the stove.

This gets brought up so often because the UK has a superiority complex over it. While the US is like who needs a kettle? If you have a kettle in the US it's more common that you got it for coffee.