Why doesn't British currency feature politicians/soldiers?

Putting historical characters on the notes is a recent innovation here. Before that it was the Queen and allegorical characters like Britannia.
Even the monarch on them is a fairly recent development. George V apparently appeared on the 10/- note, but after that none until 1960.

Two… Edith Cowan was a pollie too (the first woman elected to an Australian Parliament, in this case the WA State Parliament)…

You forgot that Eisenhower was on the dollar coin before Susan B. Also, it’s Presidential dollars, not quarters. The state quarter coins had lots of non-politicians on the reverse. Helen Keller was on Alabama’s coin, John Muir on California’s, and Duke Ellington was on DC’s, for example. We even had a monarch on one of them.

As for boring, the first real person’s image on a US coin was Lincoln on the one cent piece. That was in 1909 and it hasn’t been changed since. But they do change the reverse of the penny every 50 years to keep things lively…

Another boring coin was the five cent piece. From 1938 to 2003, neither side of the coin changed at all. Then in the space of just over 2 years, it got two different obverses and four different reverses.

Union Maj. Gen. George H. Thomas, “the Rock of Chickamauga,” also appeared on $5 U.S. Treasury notes after the Civil War: Education, Economic Education, Teaching Resources, Currency, American Currency, US Currency, American History, US History, Exhibit | San Francisco Fed