My one quibble with the article is that calling Reading a suburb of London is quite misleading. I understand (North?) Americans use the word differently to Europeans on the whole, but Reading is a Medieval town with a net commuter flow inwards - it's the local hub of economic activity, and is the largest town (it hasn't got city status) in the UK.
For context, in terms of its economy, size, distance from London etc, it's not much different to calling Oxford <edit>or Windsor</edit> a suburb of London.
We often call smaller city's suburbs of larger ones. DC 'suburbs' extend out 60+ miles and include several mid-sized city's. "Greater Metropolitan area" is often a better term. EX: Fairfax city is in a similar location relative to DC and takes 1h 20min to get their by subway, it's also inside fairfax county which has ~1Million people. However, large numbers of people commute from west of Fairfax into DC.
So IMO, it's consistant when you look at overall traffic / commuter flows.
I think the term loses a lot of meaning if used just for the same distances in the UK as in the US. Particularly because the main consensus for 'suburb' seems to be that it's a residential area, which the commuter flows suggest that Reading is not. Perhaps the best benchmark is merely whether a place is treated as a sub-district (albeit far-flung) of a city? I'd say that doesn't apply to Reading, but perhaps the same is true of Fairfax.
Your final remark is a little confusing - what is consistent looking at commuter flows? You mentioned that large numbers of people commute from west of Fairfax into DC, and I said Reading has a net influx of commuters. Those statements don't directly contradict each other, but certainly don't explicitly agree!
Suppose 100k people live in fairfax and 150k people work in fairfax. That's a net influx. But if 300k people commute though fairfax IMO that point's to it being part of a larger collective.
This really bothered me in the article too, though I'd always assumed Reading was a city (it certainly _feels_ like one!) - thanks for the info on that
For context, in terms of its economy, size, distance from London etc, it's not much different to calling Oxford <edit>or Windsor</edit> a suburb of London.