/ I was born in Poland and I cannot pronounce 'CZ'
Well. There's your experience and there's mine hehe.
Anyway. Those things regardless of how annoying to you may be are just nuances. It's a level on par with English speakers trying to ask me about Katarzyna's whereabouts by saying "Where's Kasza?":). It's just a question of practice. Nothing more.
Vast majority of Poles using English on daily basis (Poles abroad) are self taught (like myself), never had a proper lesson and a tutor. Most of them have never seen an English dictionary yet after a year or so in the UK they are able to talk with natives about their work and even meet with then in a pub after the work to have a relaxing chat (ignoring nuances). Now imagine a generally lowly educated British "Bob the construction worker" coming to Poland and after one year going to "knajpa" and having a chat in Polish with the natives there. I can't see that happen.
Now IMHO there are two major reasons to that.
1. Poles are used to barriers in languages since they were fighting to beat the extremely complex Polish grammar from day one of their lives,
2. English (up to pretty high level) is EASY (yes I said it) therefore they don't really need to learn it properly (just being submerged in it daily is enough) and are basically unaware of the subtle nuances you mentioned above (since they were never taught about those).