Greed or Ignorance?
"Instead, Apple tells customers that they must replace the entire screen, at a cost exceeding $600, apparently in order to increase Apple’s profits at the expense of the customer."
Let's be honest, the geniusesidiots handling the service repairs probably don't know how easy it is to remove the screen or simply don't care. They type the word "screen" into their computer and it spits back $600, that's basically it. Apple isn't paying them to think.
Of course, if we're talking third-party licensed repair services, then they need to make back what they paid Apple for the privilege of touching the holy device in the first place.