Because defending the country is a lot different than the supporting the joys of suburban living.
Note that defence vendors in the USA and many western countries dictate terms all the time. This compromises defence capability – look at the delays to Australian naval air defence capability because the politicised vendor couldn't deliver air warfare destroyers on time or budget but couldn't be held to account either and held the RAN over a barrel of a gun.
Or look at Boeing a company that has been described as political lobby group that happen to makes airplanes.
It's compromising your defence when they can't deliver functional KC-46 tanker on time.
Yet they went nuts to ensure Airbus didn't get the contract including having the competition restarted when Airbus won it and then convincing key parties to make all matter of exclusions and rigging to ensure Boeing won.
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The vendors should be there to support defence forces, not there to gorge on captive and highly politicised markets.
Eisenhower's warning still rings true to this day!
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Oh and in the Israel-Croatian example I gave, there was no Lockmart guarantee involved, the Israelis were guaranteeing 3 years operations themselves.
It did involve Lockmart losing money to Israel and in the long term sales of anywhere up to 300+ ex-Israeli F-16s as they're retired (though most countries won't touch these with a barge pole due to age and high usage in combat situations).