The level of ‘downgrading’ assumed for export products from the US is highly misleading. Usually it’s just a matter of some specialised radar functions removed, communications security and so on. Or stuff like ensuring the weapon can’t target geo-coordinates within Israel… It’s pretty hard to tweak a weapon so it under performs by any significant amount.
Countries that have major security agreements with the US also get access to the highest level stuff – as identical to that on issue to the US forces (NATO, ANZUS, FMF, etc).
Also its in the US’s interest to promote military strength in its coalition allies and fellow travellers. The US is very much behind the concept of a global ‘western’ army as typified by the US Navy’s “1,000 ship Navy” concept. Since western countries have common strategic aims, having common military capability promotes those aims. I don’t think the USG is very much concerned that the UAE (for example) is about to double cross them and ally with Iran!
And if the US had a double cross and had to fight against the military capability of a former ally then while the technology of some systems may be equivalent the US has a whole range of un-exported capabilities – Electronic Attack, Stealth Bombers, SSNs, F-22s, etc – and control over many of the supporting capabilities needed to make exported systems operate like SATCOM, logistics support, etc. So they retain a healthy military overmatch.
The US is an aggressive and extremely fair exporter of military products. Since countries can actually buy their products as part of wider US military orders (FMS) they can actually do so without paying a slice of development costs and with high assurance that the price they are paying is actually the cost of the system plus 8% profit. If you want to buy Russian or from Dassault or others you don’t get these sweetheart deals unless the government of the source country foots the bill and no-one is doing that anymore.
