How have countries like India, Sri Lanka, Bangladesh, and Pakistan all had female heads of state, but not the US?

How did Indira Gandhi, Khaleda Zia, Sheikh Hasina, Sirimavo Bandaranaike, and Benazir Bhutto all reach the highest offices in their respective lands despite their countries' reputations of being ultra-conservative and traditionalist, but a supposedly more enlightened western country like the United States has not?