But is it fair to say that observers with more samples have a better vantage point than observers with fewer?

Yes, of course experience can be very valuable! However, it's rather tricky to share with people you don't know. You can't just make a bare assertion:

"Life is much better in Europe than in the US."

"How do you know?"

"Someone said so on the Internet."

You see? It doesn't transfer.

I think it makes more sense to tell stories of specific things that happened to you, and let people make their own generalizations.