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The last time Iran had an elected, secular, parliamentary government, the US and Britain overthrew it and replaced it with a dictatorship, one of the world's most repressive. This was 1953, when they staged a coup against Prime Minister Mossadeq, after he nationalized Iran's oil industry against the wishes of the British and US oil corporations.
The US and Britain engineered a transfer of power to the Shah of Iran, who ruled the country as a police state from 1953 until his regime was overthrown in a revolution in 1979. The Shah's regime had one of the world's worst records for atrocities like torture and killing, and was US-supported throughout.
Another reason why life was more pleasant in the US than in Iran is because the US both fought Iran directly and supported Iraq in its fight with Iran during the "Iran-Iraq War." One of the things the US did was to supply Iraq with materials that Iraq used for making chemical weapons to use on Iranians. The US knew that this is what Iraq was doing when it was supporting Iraq.
Prior to 1990, the US supported Iraq's government (which was led at the time by President Saddam Hussein) for many years while it was committing major atrocities.
The US had been interfering in Iraqi politics for many years, including fomenting and abandoning Kurdish uprisings and trying to assassinate the leader of Iraq, the same one that was later overthrown by the organization Saddam Hussein belonged to.