&gt; the limit case of which would be an arcology of extremely dense, extremely expensive housing surrounded by cardboard slums.<p>If having people live close to each other is economically beneficial - and it seems to be - then social policy should encourage that. It&#x27;s much easier to move the people to the jobs than the other way around (see e.g. the report discussed in <a href="http:&#x2F;&#x2F;www.theguardian.com&#x2F;news&#x2F;blog&#x2F;2008&#x2F;aug&#x2F;13&#x2F;timetoabandonnortherncitie" rel="nofollow">http:&#x2F;&#x2F;www.theguardian.com&#x2F;news&#x2F;blog&#x2F;2008&#x2F;aug&#x2F;13&#x2F;timetoaband...</a> ). Even in the &quot;crazy&quot; limit, if we ended up abandoning the rest of the country and moving everyone to London because we were more productive when we were all closer together... well, why not?<p>(cardboard slums are unlikely; houses outside London are cheap and large precisely because they&#x27;re less well connected. More likely outside the arcology would be retirement mansions or the like)<p>&gt; A very big factor is that London gets to have a proper state-owned local-government-controlled integrated public transport service, TfL. Most other places have to put up with private local monopoly bus services run by Stagecoach.<p>Manchester has a very similar body, and the other PTEs are also fairly similar. Several cities had referenda on establishing elected mayors with similar authority to that of London. A lot of TfL&#x27;s advantages are simply a reflection of London&#x27;s willingness to spend money funding them (e.g. Crossrail is partly funded by an extra business levy).