Because agents make things up to pacify the customer, and get them off the phone, especially when the pax is forcefully expressing their point of view.

Some days this forum has as many as half of the threads with OP's wondering if they received the straight skinny from an agent. The reasons for their posts is almost always to get verification/support that they were in fact safe, or questioning if somehow they could get around paying the change fees.

Then their are the folks that never look at their itin's until T-24 and the advise given to them is to contact the DOT or UA Insider. Oh, yes sometimes IMMEDIATELY contacting their credit card co is suggested as a first avenue of relief.

IOW's, NEVER, EVER take the word of ANY agent - EVER!!!