Good question, do Slovenia though has a local exchange? If yes, then they can track everything and put that 10% tax on their people.

If not, then the only method I can think of is that crypto enthusiast will have to report it to their local tax authorities. Now, it's just the question of morality, are you going to report your personal crypto profits or not? Are you willing to take the risk and hide before the authorities have to find it out?

Trading of anything including cryptocurrencies have always been subject to taxation. I've even seen up to 30% tax on trading profit. A lot of countries already have such taxes on cryptocurrency trading so it is not a new thing for "others to follow" after Slovenia does it since they are already behind themselves.
As for "transfers" you can't tax them at all unless they tax the businesses accepting bitcoin payments for each payment which is a different story.

Answer to your first question :
*Everyone*
Explanation:
During the pandemic the government of most countries are in a tight spot and also at the same time there are many things which they can profit from and one of them is cryptocurrencies like bitcoins, online gambling is emerging as a new market, one in every 4th person in the UK is a doing online gambling, what else could you get more profits from ? Taxation? Revenues? It's all something that the government looks for in profitable sector. What we should be worried about is a *fair tax* since at the end of the day in some places the tax is as ridiculous as 64% !!

Now your second question:
Whenever we talk about KYC being asked etc.. why do you think all of this exists?? Well people are being tracked by the government most of their lives, most wallets needs to be in with the norms or they will be banned therefore the wallets you do use, they are forced to supply your information indirectly in the database. Your taxpayer ID is usually connected to your bank accounts as well and any +/- would be seen as it is.

So if I understood correctly, you wouldn't get taxed if you HODL the specific crypto you have, but once you have converted it into cash, that's the time you need to pay taxes. So if you would go through P2P, I think that's where they could get the information on how much to tax on you or something like that. The history of your transactions is in there, so; I think that's where they will go.

From the OP I take it that the Slovenian Government are taxing the act of exchanging
and are proposing another tax on the value itself.

In my country we pay 33% capital gains tax if we sell an "asset". the 33% is on the profit.
Bitcoin and crypto are classed as "assets"

Most countries have some form of taxation but what the Slovenians are proposing is
like a double taxation, thats OTT IMO.

Maybe use a forum search engine and find information that already exists in a topic that was opened almost 2 months ago?

Slovenian crypto tax proposition

Slovenia has already had very favorable laws when it comes to crypto, and what is now proposed actually goes to the advantage of small investors - the amount of up to 15 000 EUR in one calendar year will not be taxed. Most EU member states have laws from the taxation of cryptocurrencies, but each country has its own position on this - my central bank does not recognize cryptocurrencies and puts them in the category of nothing, but at the same time, the tax office puts them in the category along with shares and thus collects taxes on capital gains.

The fact is that most politicians in the EU have no idea what cryptocurrencies are, but that does not stop them from collecting taxes on them. In Germany you don't have to pay any tax if 1+ years pass after you bought the crypto and then sell it, in Croatia the deadline is 2 years, and they say that in Portugal there is no tax on crypto at all.

That's exactly what I was thinking. How can they tax a decentralized crypto? There is no way one can trace the ID of person associated with a particular wallet i.e BTC is Pseudo-anonymous. And that's the ideology of BTC and that's why govts are mostly against the crypto since they cant tax it.
The point is crypto that comes via centralized exchanges is not what Satoshi has created, don't call it cryptocurrency rather its just digital currency.

The countries in which people use cryptocurrencies and cryptocurrencies are not banned will choose to impose a tax on them of course. And all of the countries like this will follow each other in doing this too. This is really an inevitable thing to do as people are making a lot of money in this market. There are even so many people who make a living thanks to the crypto market. So, governments wouldn't prefer just letting people continue like this without paying any taxes.

Actually, even a %10 rate is big for taxing cryptocurrencies to me. But taking the action the USA have taken about this into account, this still seems to be a reasonable tax rate compared to it. Because the US government imposes an income tax on the cryptocurrencies. Earnings through cryptocurrencies are seen as income in there. When it comes to whether other governments will follow, I think that they will.