Is it because they like it, the flexible working hours, never a dull moment, the pay
I like it. It's a fun, varied job that requires a hell of a lot of thinking on your feet, combined with being absolutely required to be flexible. But it's worth pointing out that my day never starts earlier than 8am and never finishes later than 3 - and I only usually work 4 days a week. To have a 3 day weekend is great, and for instance - I managed to take a week off in May to go to Croatia because we closed the school rather than open for 2 days out of 5 that week.
But it's worth pointing out that unlike most English teachers working in language schools, I'm paid a set salary regardless of what I do - which makes a huge difference to my quality of life.
Or was it a last resort, because they did not find anything else?
At least in my case, it's what I always wanted to do. I dabbled with self employment for a while, I had a business idea that was working - but I was offered a great job in a school. It was a no-brainer - it would have been foolish to throw 60 hour weeks into self emloyment when I could do less than half of that in a proper job.
Teaching is an option that doesn't require you to speak Polish
Funnily enough, I think I'd be totally lost without being able to speak Polish. All the meetings and so on are always in Polish because most of my colleagues don't speak English - I was particularly proud a few weeks ago of having made quite a detailed plan with a colleague - all in Polish.
It is only I often see people looking for an "ordinary" job in Poland, without knowing any Polish at all, and then starting to ask if they can earn a living on teaching.
Indeed. It's often (at least for English speakers) all they can do - particularly for people involved in business that can only be done in the native language. I think it's madness to come here if you're already well established in your own country in a field that can't easily be transported to Poland, however.