So you want pre-built ghettos by the government? Besides morality,
In the UK, and some other states; there is a need for more housing to accommodate:
(a) migration from low lying areas
(b) existing homeless
(c) replacement of old and energy inefficient buildings;
(d) increasing elderly population;
(e) accommodation of refugees; and
(f) accommodation of skilled migrants (e.g. dentists)
Now (f) ought to go where the demand for their labour is.
Categories (a) to (e) could be housed in new towns.
It is not about building towns specifically for refugees or requiring
them to live there; it is about strategically building more capacity.
that is also the most expensive solution. It‘s much cost-efficient (and also benefitial in the mid-to-long-run
as studies have shown) to settle them down somewhere where they can contribute to the economy.
It may be convenient for Angela Merkel's budget to invite the refugees in and then
suggest they are distributed around the EU, they become someone else's problem;
and for David Cameron to volunteer the UK for 30,000 Syrian refugees and then
distribute them around the UK (local council's problem); but it is not the most efficient way.
The things about costs is that total overall costing is rarely done (in the UK).
It is usually about particular peoples or organisations' budgets.
If one lets the refugees acuumulate in the most densely populated cities such as London;
two costs are incurred; (a) paying for renting the relatively higher priced accomodation there;
and (b) the increased costs that all the other people already living there or migrating to work
there encounter due to the result of the excessive demand driving rents going upwards.
The UK government is very much aware of (a) but simply pretends that (b) does not exists.
Now a business case for a new town can take into account both (a) and (b) costs.