Because they believe you are customers.
This is no different than me approaching Verizon or at&t and demanding they peer with me.
This is no different than me approaching Verizon or at&t and demanding they peer with me.
For several years the TELUS and Bell peering PNIs (OC12s back then) would run hot regularly in domestic Canada - for years.
You'll never get them to peer openly, but at best you can get them to offer market rates for paid peer (which is what folks have tried to do in the US).
Maybe I’ve got it wrong, but don’t my peeringdb links suggest Bell and Telus do peer openly, but only on US soil?