The EU’s quotas — allowing quantities of certain products to be imported at special lower-duty rates — are for the whole single market, not any individual country such as the UK. Limits on agricultural subsidies are also for the entire EU.
To be an independent WTO member, the UK would be creating its own rights and obligations out of the EU’s. That’s not as simple as it sounds...
Take just one hard-fought issue: low-duty import quotas for high-quality beef, just two of almost 100 EU quotas. The EU opened these beef quotas after lengthy negotiations with Argentina, Australia, Brazil, Canada, New Zealand, Paraguay, Uruguay, and the US.
Extracting UK beef quotas out of the EU’s would require negotiations with all of them, plus possibly other suppliers such as Botswana, India, and Namibia, and definitely the EU itself — Ireland, Germany and France have particularly strong beef lobbies.
While the exporting countries are pressing for the UK’s quota gates to be opened wider, and jostling with each other for paths through the opening, UK farmers would be pushing in the opposite direction. Remember, to reach agreement, the WTO’s consensus rule would apply.
The EU’s black hole
Now comes the surprise. We don’t know what most of the EU’s current commitments in the WTO are. The UK would be negotiating a share of key quantities that are unknown.
The only confirmed commitments on tariffs, quotas, and farm subsidies are from before 2004 when the EU had 15 member states. The EU has expanded three times since then, but in 12 years it has been unable to agree with the WTO membership on revised commitments.
That in itself is a warning. The UK will be negotiating a share of numbers that are unknown, with no guarantee of agreement...