I happen to know the person in the article. I was also an intern at Google this summer in Europe.
edit: In fact, for a lot of people, that is insanely good! Apologies if I came across as an asshole when I said "for an intern".
Also, it's a lot less than what competitors pay interns in London (Bloomberg, Facebook and Palantir pay interns a LOT better, among others).
In Poland, ~1000EUR/4000PLN/month is more than what an accountant makes. Teachers never reach this salary, even with 30+ years of experience.
You can easily live very comfortably on that salary, if there's two of you making that money you can buy a house and pay it off within 10 years or build one.
Being paid that much as an intern is just unheard of, most people I know would trip over and faint if they heard this.