Go to any local supermarket and see which currency they are completely comfortable with. It is always cash and will be cash for at least a hundred years in the future. Digital payments have go up but it still uses the same fiat currency in the background - just that the payment method is easier and you would not need the cash physically.
Paper money is actually the most convenient way of making payment and it is accepted both by the young and old. Outside the supermarket even the local markets where we get foodstuffs and all we won't imagine a granny who doesn't have experience tackling the digital world accept digital currency. First she might even label the payee as a scammer or another name that suits them.
In such situations bitcoin is least known in some countries but might be popular in few, but it is not so in some. Things might change in future, but we only represent a small subset of the world's population.
Bitcoin been the least know in some countries used to be the case when Bitcoin suffered price fluctuation. I doubt if there is any country currently that doesn't know about Bitcoin considering the hike in price experienced decently. I sure Bitcoin is been secretly held by most countries who criticise and set strict regulations around the asset. As it stands the entire population has a good