Are most of the Polish IT companies trying to enter into the U.S. market
Yes, but you can get an American copywriter for not very much money. I hired one to do some incredibly dull work, and it cost us less than $75USD per full day of work, and he had to pay taxes on that amount.
Polish businesses are price sensitive, and in our case, where the copywriter was producing some materials for an educational project, there was simply no need to pay any more. The guy was happy to get a week's worth of work, and we were happy to get someone who perhaps wasn't the best writer, but his work was grammatically correct.