[geezerjay]

> I've got two friends, one lives in Wimbledon (far south), the other in Barnet (far north).

That isn't a fair assessment. Metro lines are used to enhance mobility within urban areas. Their goal is to replace cars and 20-30min walks with a 5-10 metro ride with an additional 5min walk. That's why typically subway stations are placed about 500m to 800m apart, and the system's commercial speed is designed to be around 50km/h.

For long commutes, such as going from far north to far south, there is an entirely different system: commuter rail. Their stations are further apart, their commercial speed is higher, and so is the passenger volume.

Just to provide an example, Madrid is served by both rapid transit network (madrid metro) ans a commuter rail system (madrid cercanias). It takes between 30 and 40 minutes to cross Madrid riding the metro network, but the commuter rail takes about 15 or 20 minutes.

[talldan]

That's an ideal and not actual reality.

Taking London as an example, there aren't many ways to cross London in such a way using commuter rail (ThamesLink currently and Crossrail in the future are probably the only two?). Most people would still use the tube.

That's why 1hr + journeys in London are not uncommon.

(edited to add) London and New York are also much much larger cities than Madrid. It's not really a fair comparison.

[asib]

It is a fair assessment, because I did take into account commuter rail, which is not any faster - a quick Google maps check says both tube and rail (of any form - overground, national rail, etc.) journeys come to around 1 hr 40 mins.