I'm not sure that is less friction. Chrome already can and does store my contact and payment details, and the alternative is downloading and running some part of a custom app that integrates with Google pay?

Somewhere I have to choose what card I want and what address to send the item to, both of those are already handled pretty well in chrome. The problems come with poorly made forms on sites, but I dont think comparing bad sites to good apps is fair.

I'm not trying to be contrary here, I've just not seen a decent reason for these yet. Really they're like websites but with a different API that's not cross platform. I guess a good integration has to be one that can't be done with a website, a user also doesn't need regularly and requires no special permissions.