This an entrance to Dupont Circle station on the Washington Metro.
Notice that the escalators come up to street level.
Why don't they in London?

Washington stations generally have large excavations at platform level:
even with outside platforms, as at Dupont Circle, there is generally a
single big tunnel including both tracks and platforms. Therefore there
is room within the tunnel for a mezzanine level with the ticket machines
and fare barriers, and that's where they're usually placed. With this
design there is no reason for another intermediate level before the
street, and typically there isn't one. (There are exceptions: at
"Woodley Park - Zoo - Adams-Morgan" station, which is deeper than
Dupont Circle, the main escalator stops below street level and there
is a shorter one for the final rise. I don't know if this was done to
protect the long one from the weather, or for other reasons.)

In London the space excavated at platform level is minimized, so the
fare barriers are typically either at street level or just below, and
if there are long escalators to reach deep platforms, they run down from
there. Between the ticket office and street level, if there is a climb
at all, it's typically short enough that no escalator is needed.

I expect it rains more in London.

But it snows in Washington, sometimes it really snows.

I've had a think about this, and whilst there are lots of escalators on
the London Underground that do reach street level, I honestly can't
think of any that do so in the open air. I'll crosspost this to
uk.transport.london to see if anyone knows any better.

In fact the Washington system has had considerable problems with escalator
reliability; having the escalator heads exposed to the weather may not have
hurt much, but it cannot have helped.

One day the last time I was there, as I approached the exit barrier at
Dupont Circle I saw people walking up the escalator in front of me, but
I went ahead anyway, as I knew the station also had an elevator and
I didn't mind waiting for it. Only after I was through the barrier
did I realize that the elevator was at the exit at the *other* end of
the station...
--
Mark Brader "Exercise 5-3: ... When should you
Toronto have stopped adding features...?"
-- Kernighan & Pike

My text in this article is in the public domain.