Is it just me or does every polish person think that if you live or come from the states that you must be very comfortable financially?
I am sorry you're struggling and let me tell you that I too have been there and done that. If at all possible MOVE from Detroit. It's the armpit of America (apologies to those who live there now ;) and there are very few jobs available in that region, you'll make your life better by moving somewhere else...
(I just re-read your post and it looks like you live in Poland now?)
As far as your mother who "works for Florida state gov" - what's your point here? Should government employees get better deals? I don't think so, federal and state government jobs should be a temporary solution until you find something better. Ideally 95% of government jobs should be turned to the private sector.
The ability to get credit is much more restricted today as opposed to just a few years ago; it probably makes sense as many people who couldn't afford houses bought houses using easy credit hoping for "better times" which of course never materialized. You say it's hard to get a credit in America but only a few years ago a business program on CNN showed how a dog, yes a dog got approved for a $30K loan when the owner jokingly applied in his dog's name and used a $20K income as a reference. That's right, the dog was approved for a $30,000 line of credit. The program was meant to show that it was too easy to get credit, not too hard.
Today the banks are probably more paranoid than necessary but that's somewhat understandable. Either way, I think a 15-20% downpayment on a house is a logical and prudent request from the banks.
I'd imagine that most Poles realize that the majority of the Americans are blue collar workers, just like in Poland. Either way, I'm very sorry you struggle/struggled, hope things get better for you very soon.