Poles are taxed on their world wide income
It depends. If someone spends less than half the year there and also severs certain other links, their income from outside PL isn't taxable.
Additionally, if an income derives from elsewhere and is paid into a bank account elsewhere, there's little if anything that the US can do.
Poles are taxed on their world wide income, there are structures in place in Poland which are far more beneficial than you would find in the Austria,Switzerland or the UK.
This is true.