Are these lottery sites scams?

These sites are:
http://www.bestlottousa.com
http://www.bestlottousa.ru/index.php

People claim that they have won small amounts of money and even some friend has won 20 million?
I myself reside permanently in Latvia, but these lottery sites claim that people from all around the world can buy tickets on-line and win true money. Can I trust these sites and play lottery on-line having real and trustworthy chances to become a real money winner?

They are illegal.

Here's the official statement from Powerball:

Any Internet lottery site that purports to sell Powerball tickets, or “shares” of Powerball tickets to purchasers or to run a “service” for you, is operating illegally. They are not authorized by the Multi-State Lottery Association or by any U.S. lottery. There are legal Internet sales of lottery tickets in some states or countries, but only within the borders of that state/country or by agreement between nations. The United States has no agreements with any other nation to allow lottery tickets sales across the national border.

In other words, NO online site selling US lottery tickets across borders is legal. You could buy lottery tickets if you visited the US, and if you won, you would be eligible to win. In that case, your passport and plane tickets would serve as proof that you were here in the US.

Even if the website provided you with a real ticket, in order to claim the prize you would have to be able to prove you bought the ticket in the US--if you couldn't (which of course is the case) you would not get the prize money. Any attempt to bypass that rule would be fraud, and could get you into a lot of trouble.

Why then such illegal lottery sites are operating freely in the world? Just because no one has courage to start sueing them?

The number of fraudulent websites operating illegally around the world is phenomenal. A lot of people work unpaid trying to get them shut down but it's a monumental task and there's usually very little chance of prosecuting those responsible.

The best method of fighting is to educate people what to look out for and, as well as getting them shut down, this is one of our aims as well as helping to point out which ones are scams. If they never manage to snare any victims they'll stop.