It’s not that slow. 1. They sell plenty of kettles in the US (touch grass and go to Target sometime or something) - a large portion of those sales are probably to Asian households. It is simply that if you have a drip coffee maker and don’t drink much tea why do you need a kettle.
No idea where this dumb myth comes from - kettles are not hard to find in the US, they work fine - there is a ton of demand it is just relatively miniscule.