"cost of replacing all the card reader infrastructure"

I'm not sure how many PoS are already equipped to deal with chip cards. In the USA/Canada it's hit or miss (most misses), and in Europe it was the standard 10 years ago (but most readers take swipe cards).

Replacing cards is cheap and they can be replaced as they expire

What would be the upgrade cost for each PoS? $100? Some systems are more integrated than others (like card reader integrated with the register as one device) so this may cost more.

Or maybe it's just a matter of issuing the cards to justify the stores to upgrade.