Apple Pay and Wallet Settings page on Mac not syncing with Apple Wallet Settings on iPhone? Why not?

The latest macOS allows you to use Apple Pay on sites in Safari as a quick Apple Pay option. But, it does not add/sync the cards between the two devices (iPhone SE and MacBook Air, both with latest OS updates). This makes no sense to have to manually add a new, or updated charge card to both when they are both integrated in every other way.

I don't see any security issue that would necessarily require this. Having them not sync seems to be a security issue, not a benefit. Both require verification (touch id, etc.), so there should be no security issue when using Safari. What am I missing and when should we expect this issue to be corrected?