There is nothing to be surprised. Still there are a lot of people around the world even did not hear about Bitcoin and American people are no different of course. Even those who heard about bitcoin to them it's a scheme or something which will pop up soon.
We are sill in the early stage of bitcoins.
Up until now, people who are into crypto is a very small percentage among global population. So yes, it's not really surprising even if we are already in the digital age. Maybe a lot of them have heard bitcoin, but I don't think ethereum will be familiar to them. The thing is, even if they heard about bitcoin, they don't even know where to start, or how to deal with it.
Or maybe they already heard about it but didn't try to look forward to it or they are not interested at all, coz even if we adopt bitcoin to a new level there would be more people that will use fiat and other payment method than cryptocurrency. The crypto community now is in its biggest since the beginning, but it does not mean that the world already has it. It is global, yes, but not everyone knows about it. However when you tell someone or said the word crypto they will mostly think of the bitcoin. If someone really wants to know it, they would not mind searching to it.
But if big companies will start to accept bitcoin and other alts as payment method, maybe it will start the adoption stage to the masses or regular online shoppers.
As far as I know there are already companies who are trying to adopt it, the most recent rumor is with Paypal and Venmo, I honestly think they could really help crypto to grow.