you cannot copyright a drawn apple with a piece bitten off
That's correct, you can not do such. Apple does not litigate its logo with copyright but in trademark disputes. Prepear and Georette are examples of this.
You too can create a logo of an apple with a piece bitten off. It's up to a court to decide if it's coming too close to the Apple trademark, most people want to just avoid that and settle amicably, but if you've got to the pocket change to fight it in court, you can argue that your bitten off apple isn't a trademark infringement.
If you find a company that isn't keen to defend their logo, you can totally get away with it. Apple is on the other end of the spectrum of being someone who will protect their trademarks to the bitter end. Jack Daniels and Disney are two more examples of companies that will legally punch a five dollar start up into a bloody mass over trademarks.