Eh close to free. This is the Google edge nodes in ISPs. But Google isn’t the only one with such an arrangement. Akamai, Netflix and a few others have same cost structure for in isp nodes.

There's a big stand-off between ISPs and CDNs over payments. Some ISPs insist they want payments to peer and others agree that it's mutually beneficial, but even where the ISPs stamp their feet, they rarely win the argument. Netflix started publishing rankings which showed which ISPs were good and which weren't, which drives them to improve. If content providers start saying to customers that they should change their ISP, then the ISP is going to hurt, so they might as well peer on a neutral basis.

Some ISPs have been lobbying governments and the EU to ask them to tax the "significant traffic generators" based on the traffic volumes and then use that to pay for the telco infrastructure. But that's an argument I am not convinced by, I think the ISPs will take the money, just reduce their own investments and make more profit.

I think the CDNs (including Google) need credit for the infrastructure they build.