In the US, your gains from Bitcoin (or whatever) are taxed, which is also true in many countries. Yes, you can fail to claim your gains on your tax return and not pay those taxes, but you can do that with any kind of investment.
I don't think so. I'm not in the US, but it is far more difficult for a tax authority to monitor every transaction across all banking systems and question each one to determine whether you realized your Bitcoin gains than it is with other investments, where regulated intermediaries often report directly to tax authorities.
In my place, gold coins are bought and sold, and I am very sure a large portion of those transactions and gains are not ever reported. I can imagine the same with peer-to-peer exchanges in bitcoin.
Tax evasion in the US has been happening since taxation began. Bitcoin did not invent tax evasion, and it doesn't even really make it much easier since you would need to engage in tradecraft to create fully hidden transactions if you wanted to be reasonably sure the IRS couldn't track it down.
99.9% of consumers actually
want their tax compliance to be handled automatically so they stay out of trouble.
If tax evaders is the audience for Bitcoin, it's an extremely small one, and one that will support a market cap of no more than a few $million, not billions and certainly not trillions.
Oh, and once again, this is an even worse advertisement for Bitcoin since it has a
public ledger so if you are going to use it break the law, it's simply not as good at that compared to Monero and things like it. Hence the argument, "buy Bitcoin so you can evade taxes" doesn't even hold water on its own terms.