Exactly.

Could use other cash/crypto currencies etc..

There's an interesting problem I didn't think of. I assume governments/banks/CC's etc.. will want to get rid of cash ASAP in society, however... you would have to make it illegal to accept other forms of payment before hand....otherwise businesses and capital would just choose the "more freedom" option if it was beneficial to their business. So you would have a form of capital flight if one country tried to get rid of cash and others didn't.

All of this just leads to more state control, more boogeymen to scare the public and ultimately more clamp downs on freedom.

The divide between people who use the "underground" and the "mainstream" will be extremely wide soon.

Many will exclusively work underground and collect UBI and use cryptocurrencies etc... store other cash and assets all out of the country. On paper they will look like deadbeats.

On the other hand you will have the remainder who suffocate on taxes and demand further clampdowns.....

Doesn't seem that appealing to me.