I think every country is different, and while in Italy on a fiscal trial it's you that you have to prove that you are innocent and not the state that has to prove that you are guilty, it's still a civil trial and that normally takes 10 years to complete. Then they have to get your money, that's why mostly all big famous trials ( Valentino Rossi and such ) ended up with an off the court agreement. So I'm certain that they are looking on the internet, but I''m also certain that there is a certain threshold you have to cross to make you a fish that they want to catch, because catching you requires work, and there might be bigger fishes to catch. Also in italy delation is not common, while in other countries it's the norm, because in italy mostly everybody performs some degree of fiscal crime, and even if you don't, if you want to live a quiet life, you mind your own business.They spend most of their days browsing the web in order to find their next victim. Then they prepare the “operation” and one day, in the early morning, show up at the victim’s house to execute it.
They love to harass naive and defenseless people.
And of course they start at the top: if you paid taxes in italy for 10 years, and they know how much money you were declaring in italy, they have more data on you: that's why they offer you a 70% tax discount if you go back to working to italy, because they f**k you in the long run. Most of the controls is on people putting residency back in Italy after living abroad. A friend of mine who owns 4 houses in London, went back to milan with the fiscal discount, when they discover the houses and the fiscal discount is over, they will f**k him well...