Because Norway’s deal would be a bad deal for Scotland. Even assuming it could be negotiated, we would have to pay substantially to trade with the EU, would still have to implement much of the EU rule book, but would lose all our say in what it looks like.
The European Free Trade Association (EFTA) is a trade pact that negotiates treaties with various nations on behalf of its members: Iceland, Liechtenstein, Norway and Switzerland. EFTA and the EU have agreed to create the European Economic Area (EEA), an extension of the EU single market. Switzerland opted out of the EEA agreement, preferring just EFTA. Norway is part of the EEA single market, as is Iceland and Lichtenstein.
A single market must have a single rule book. The nuts and bolts of trade need to be defined and it is this sort of regulation that the EU spends much of its time working on. This process does not involve EFTA countries, and nobody represents their interests. The EFTA countries are simply presented with the law and a deadline for implementation. They tend to implement faster and more accurately than any actual EU member state.
The Internal Market Scoreboard from the European Free Trade Area Surveillance Authority revealed that the best country at implementing EU laws and regulations is... Norway. Better than Scotland, the UK, Germany, Ireland or, indeed, anyone.
And that matters, because the regulations adopted are not peripheral and cannot be ignored. They are at the core of the single market and include energy, transport, company law, free movement of labour, free movement of capital, state aid, competition law, procurement rules, and lots more besides. And Norway signs up to the lot without a say over any of them.
On top of this, Norway contributes, vastly, to various individual EU programmes. One example of this is the research and innovation programme, Horizon 2020, which has provided excellent opportunities for Scottish universities. Paying towards these extras and paying for the EEA mean that, between 2009 and 2014, Norway was the tenth largest contributor to the EU budget.
Of course, Norway has the democratic sovereign right to choose whatever arrangements it wants, and the means to buy its way out of trouble. But if an ‘Out’ vote looks like the EEA or EFTA, then it would create a vastly undemocratic structure at huge expense and for what gain?
This would be a real democratic deficit, but this is often simply overlooked or deliberately ignored for the purpose of political point-scoring by euro-sceptic politicians.