> you should be able to name an expert in these skills

There are certainly local “finding information online” experts in many families and social groups.

> and how do we know they are an expert

They are the ones who get mentioned a lot in conversations in the manner “I'll have to ask [name]” with the implication that [name] will look up the information or know it from previous occasions people (possibly this specific person and [name] is getting sick of them asking and not remembering simple answers!) have asked.