At age 20 in my country a woman (or a man) can enter into legally-binding contracts, has the right to vote, and is liable for jury duty, and generally is treated as fully and completely adult. Compared to what I was doing at age 20, Elizabeth seems very young and sheltered. All she has to think about is potential husbands.

I think there were probably a lot of differences in people's experiences. A young woman who at age 20 was already running a house and had several small children probably had to learn more maturity than a woman who was still living at home with her parents like Elizabeth did. But then, nowadays in my part of the world, a young woman at age 20 can have had several babies - she's just not so likely to have a husband to help.