You need to look at this from the other direction.
Apple employees are presented with MacBooks with cracked screens every day. When faced with the enormous cost, Owners, almost without exception, have "No Idea how anything could have damaged the screen." Some of these computers have such obvious abuse symptoms such as tire-prints on them after being run over by a car.
The standard policy is "Damage to glass is not a defect covered by Apple warranty against defects in materials or workmanship."
This sort of damage does not generally happen spontaneously. If you want a different answer, you must contact someone at Apple at a much higher pay-grade to make an exception for your specific case. You can start with the store manager, but they have already heard the same story from several irate users this week.
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If you made the decision to NOT pay for the AppleCare PLUS extended warranty, you made the decision to bear the cost of repairs during the extended warranty period yourself.