They can't turn up because google doesn't index relay notes (like nostr.band) - to do so you'd need to query relays for all the events and then store them.

A web2.0 search typically indexes hyperlinks and the links those are attached to (if a site has lits of connections to it, its assumed to be higher)

This is different because nostr events typically don't have a unique URL assigned to it like other websites.

At least thats my sky high understanding of it.