If you use bank transfers for these types of transactions, then the bank has access to all bank transactions, and in my case, that means that the tax office, as well as the financial police and maybe a few other agencies, have access to the same transactions.
Yes, but it still is better, in nearly every way. First of all, the authorities do not know that you bought or sold bitcoin. They can only found out about it if you report them what you did. If you're worried about that, you can still report everything normally, and just know that you'll buy and sell with no bullshit that has to do with "tainted coins", or whatever other nonsense they figure out to impose. The only pro that a CEX can offer to you is larger volume, and buying and selling large quantities which cannot be done peer-to-peer easily. We can agree on this, DEXs are far better for trading than CEXs because not only is KYC not required, but there is also no possibility of someone being hacked because there is no option for coins to be stored in the possession of the service being used.
However, for those who often trade through DEX, there is a certain amount of risk that their data will still be leaked to unknown people, because (if I'm not mistaken) if we sell cryptocurrency we have to provide our name, surname and bank account number (maybe even our address). If we are not skilled enough to hide how many coins we actually have, it is possible that someone would choose their targets for physical attacks in this way.
Everything you mention are great advantages over CEXs, but there's one thing you didn't take into account - and that's banks. If you use bank transfers for these types of transactions, then the bank has access to all bank transactions, and in my case, that means that the tax office, as well as the financial police and maybe a few other agencies, have access to the same transactions.
If someone can remove the bank from this equation, then there is almost a perfect way to trade with cryptocurrencies.
The problem lies in the quantity. If you want to exchange dozens of bitcoins into your fiat currency through a bank, you will set off alarm bells. But if you occasionally make transactions below the limits where they are automatically reported you will be fine. Plus I haven't used it myself but I could swear I've seen on DEX offers to exchange for fiat that is sent via snail mail. You can rent a PO box if you want to receive it with privacy but here again it matters the amount. If for whatever reason the envelope or package gets inspected and they see millions of euros you are going to have a problem but a few hundred or even a few thousand now and then is fine.Wait a minute, are you saying that there is a way of exchange in the sense that I send someone cryptocurrency, and he sends me money via letter? Even if there were such a way of exchanging, how would one ensure that both parties kept their end of the bargain? Coin in escrow until the other party confirms receipt of the envelope - what if the envelope is lost or someone in the delivery chain opens the envelope and takes the money?
When money is sent by letter, such shipments are usually declared as letters with a value that are insured for the amount contained in them - but this service also has a price.