The antimonopoly Authority of South Korea suspects that Apple charges developers a commission of 33% rather than 30%.
It is assumed that the company does not take into account VAT paid by application users when calculating the commission (in South Korea it is 10%). As a result, it turns out that Apple takes 30% not from 100%, but from 110%. Because of this, the stated 30% of the commission turns into the actual 33%.
The Foss Patents portal notes that Apple adheres to this practice in at least four other countries — Turkey (35.25%), France (32.1%), Italy (32.1%) and the UK (31.5%).