They offer similar services: a centralised place that people come to in order to buy a variety of products. It's good for your software to be on it. The differences are minor, it's the merchant solution that is significantly the same.
At least with the Android marketplace, if you don't like that 30% cut, you're free to separately market and take payment for your application. The principal part of both is this 'centralised store' approach, combined with dealing with the payment system.
The other thing is good old capitalism. Apple and Google aren't social services, so why should they operate on razor-thin margins? They have desirable products, and are charging normal retail overheads for what is, essentially, a royalty-based industry. 30% is fine, and 'what do you get for it'? The ability to hawk your wares and not have to worry about bad debts or if it's worth taking a 99c sale.
At least with the Android marketplace, if you don't like that 30% cut, you're free to separately market and take payment for your application. The principal part of both is this 'centralised store' approach, combined with dealing with the payment system.
The other thing is good old capitalism. Apple and Google aren't social services, so why should they operate on razor-thin margins? They have desirable products, and are charging normal retail overheads for what is, essentially, a royalty-based industry. 30% is fine, and 'what do you get for it'? The ability to hawk your wares and not have to worry about bad debts or if it's worth taking a 99c sale.