The same principles of "authority" apply in whatever industry. It's just relative to that industry.
Consider one (big) aspect of authority is a large quantity of topical articles deep within a site and lots of external sources (themselves of quality) deeplinking to them.
I suspect what you're actually saying is that's hard to achieve in your industry, as opposed to hard to determine "authority".
So if I were you I would be thinking laterally towards article writing and the linking of those articles. And the quality of those links need only be high relative to the industry norm.
Forget SEO. In terms of onsite content, consider why you think it's authoritative.
Then match it, but do it better.