Cash is being phased out (censored) and can't be sent via the internet.
Try and move more than $10K in cash and see how far you get.
It's not yet pervasive, but there are many retail places that don't even accept cash. Once CBDCs are in place there will be a massive incentive for the US to further restrict cash. CBDCs are the ultimate control over a state currency. They'll provide all kinds of legit rationale, but totalitarian control is along for the ride.
Censorship can be overt, covert, societal or authoritarian.
There is absolutely a war against bearer instruments like fiat cash.