

Yes, cash is still very much in use in the US. And you can pay the IRS in cash, at least for amounts less than $1000. But checks are also in use here. I’ve bought a few cars with cashier’s checks and nobody has given me a hassle about it.
However, there are certain venues now that will not accept cash at all. Theme parks, stadiums, concerts: they are mostly places where places to spend money are spread out, and the burden of physically handling the cash is a lot. I have seen theme parks with kiosks at the entrance to convert people’s cash into VISA debit card accounts just to facilitate this. I guess they think it makes it all more efficient.
I will say that while I still carry around cash, after the pandemic I refuse to carry around loose change. Why would I? I will never need to use a pay phone anymore, and most parking meters can be topped up from your phone. Anytime I buy something in cash and get change, I usually just put it in the tip jar, because there is no more room in that jar on the dresser.




I am not a dual citizen, but know several. The benefit is that you have all the rights of a citizen in either country, the chief benefit is that you can stay in either country as long as you want to, and not worry about any visa limits.
The main drawback is that you are subject to all of the regulations in both countries, and if you get in some sort of legal trouble in one country, the other country can’t help you at all. (Of course, they may not have helped either way).
If you are a citizen of a country, you often must show that passport when entering. So these people frequently travel with both passports, and when going to a third country, use whichever one is most advantageous.