Turkey is member of customs union of europe. They can trade with whomever. And they do. So, it doesnt matter, if they are full member of EU or not.
It does matter,you should first check out if matters or not.
Here’s your starter for ten: what’s the difference between a free trade area and a customs union? It might sound like a technical question, but it goes to the heart of our relationship with the EU. And it’s becoming increasingly clear that lots of people, including economics correspondents, don’t really know the answer, which makes it hard to have a meaningful debate about our options.
A free trade area is a group of states which have eliminated most or all tariffs and quotas on their trade. Sometimes, their agreement covers only manufactured goods and commodities. Sometimes it applies to services, too. In a few cases, it incorporates free movement of labour. Examples of free trade areas are Nafta (Canada, the United States and Mexico) and ASEAN (ten South East Asian states).
A customs union involves internal free trade, but also a common external tariff. Its members surrender their separate commercial policies, and give up the right to sign trade agreements. Instead, trade negotiations are conducted, and treaties signed, by the bloc as a whole. Customs unions often exist where one state administers another, or where a tiny nation contracts out its trade policy to a larger neighbour: Swaziland and Lesotho are in a customs union with South Africa, Liechtenstein with Switzerland, Israel with the Palestinian territories. Other than the EU, the two chief customs unions on the planet are Mercosur and the Andean Community. (Though Brussels was so heavily involved in launching these two blocs that they might almost be considered
creatures of the EU).
One way to think of the difference is this: Nafta could accept Britain while allowing it to enjoy free trade with the EU; but the reverse is not true.
The two models coexist in Europe. EFTA is a free trade area. Its members buy and sell unrestrictedly with each other and with the EU. They can also
sign commercial accords with non-European countries. Switzerland, for example, has signed a free trade agreement with Canada, and is negotiating one with China.
Britain, despite its historical links to Canada, can’t sign such an accord. Nor can it press home the advantage of its growing exports to China (up 40 per cent in two years, as the PM delightedly told his party conference). In both cases, it must wait for the EU to negotiate on its behalf.
We suffer disproportionately from the EU’s common commercial policy because we conduct an exceptionally high percentage of our trade outside Europe. In 2011, non-EU markets accounted for 57 per cent of our exports; the equivalent figure for Belgium was 22 per cent. The EU’s Common External Tariff averages between five and nine per cent – higher than Britain had in the 1920s.
The optimum deal for the United Kingdom is surely to be in a European free trade area but not in a customs union. Again and again, we have been forced to sign less liberal accords than we would have negotiated bilaterally in order to accommodate some protectionist interest on the Continent.
And, of course, membership of the customs union has sundered us from our hinterland. Among the countries with which the EU has negotiated no trade deals at all, beyond the WTO minimum, are the United States, Australia and New Zealand (it is lumberingly getting around to talking to Canada, long after Norway and Switzerland signed their own treaties there).
This is, oddly enough, more of a disadvantage now than it was 40 years ago, because the Commonwealth has grown much faster than the EU, and is forecast to grow at an astonishing 7.3 per cent annually for the next five years. We have purchased membership of a stagnant customs union at the expense of free trade with growing global markets.
Why isn’t this a bigger talking point? Why don’t we hear the statistics more often? Precisely because trade policy ceased to be an issue when we handed it over to Brussels in 1973. In other countries, commercial accords are the major component of foreign policy. Legislators debate them all the time. Journalists take sides. Academics publish detailed papers. Here, as in other EU states, trade has more or less disappeared from public discourse.
Btw,full members have benefits like help in infrastructure and agricultural development,Turkey would get more then France who gets the most now.
Wir wurden 50% vom ganzen budget kriegen
and threatened us with Italian military. 
