Why is Google checkout not accepted on ebay?

I tried Google checkout recently. It is actually much more convenient than paypal.

It is also as secure as any other payment system.

So why is eBay keeping such a convenient service away from its users?

Could it be, perhaps, that they keep such a valuable service away
from users to fatten their wallets with paypal fees?

And why are they saying that Google Checkout is unsafe?

Could eBay possibly be lying?
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