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As Hertz commercials say, NOT EXACTLY.
Not all gov't fares are refundable. The nonrefundable government fares are very, very cheap.
Even the refundable government fares, as Bruce pointed out, are very cheap. Much lower than most non-government fares, no matter the distribution point.
The airlines received nowhere near $19 billion.
Following September 11, the airlines were given $5 billion in cash to compensate them for the 3 day shutdown of September 11.
A couple years later, the airlines were given a refund of the September 11 Security Tax plus reimbursed for their expenses of cockpit doors. It amounted to a couple billion, total. All in all, about $7 billion, not $19.
You may be referring to the potential $10 billion of loan guarantees, of which only America West and USAir took advantage, and then only to the extent of a billion and a half.
We like to keep the discussions of facts sorta accurate, when possible.