I'm not from Poland, but they probably have prices similar to ours ... data plans are cheap, you have credit cards with offers for zero interest plans over 12 or 24 months, and the mobile carriers are unable to offer discounts like the used to, not to mention that exclusivity deals for devices are not a thing here.
So why in the world would people still buy phones from their mobile carriers?
Here its basically 3 phone brands (Google, Samsung and Apple) and although the brands sell unlocked direct most people get deals to get phones massively discounted by signing up for two years of service or something like that. Carriers lock the phones until they are fully subsidized and paid off and theyve made their money back. unlocking immediately breaks this business model.
So why in the world would people still buy phones from their mobile carriers?