State aid is not illegal.
One gets the impression that there are people who believe that state aid is totally illegal within the EU.
As far as I know the British governments have used less state aid than many other EU states and I think the Tory has been rather reluctant to provide any.
Quoting the Wikipedia on State aid (European Union).
"Under European Union competition law the term has a legal meaning, being any measure that demonstrates any of the characteristics in Article 107 of Treaty on the Functioning of the European Union, in that if it distorts competition or the free market, it is classed by the European Union as being illegal state aid. Measures which fall within the definition of state aid are considered unlawful unless provided under an exemption or notified by the European Commission.".
What the EU is demanding from Britain to have a favourable access to the single market is to provide clear information on how Britain will behave regarding state aid.
On WTO we find this.
However, due to the lack of specifications, definitions and in some cases clarifications, the WTO case is highly controversial and more of an exception than a rule. A solution to this would be a more thorough regime somewhat in line with that of the European Union. In that case, the prohibition of state subsidies would occur if the subsidies were anti-competitive and affected international trade.".
The reason so many big companies are found in the USA and China is their huge home markets and, of course, one of the main goals with the single market is the same.
And of course China will eventually be able to compete with Boeing and Airbus because they have a huge home market to build for first.
Still Apple, Microsoft, Google or Amazon and similar did not start due to any state aid, but it starts to become rather corny when a company like Amazon on a profit of 11 billion pays no state tax at all.
On the whole I think this article was rather unnecessary and of no value like perhaps my comment too.