Can someone explain me why the economic growth of a company is irrelevant in determining the option price. Especially for options with a long maturity e.g. 5 years it seems to me that for a high growth company this can make a lot of a difference ?
Estimated economic growth is built into the stock price. Therefore it is, albeit hidden, inside any model that takes stock price into account.
One of the puzzles of pre Black-Scholes world was how to incorporate projected growth into an option price. One of Black and Scholes' (and Merton) main realizations was that they didn't need to parameterize growth (or any other thing discounted in a stock price.)