The point you raise is exactly correct; which is why we've set up
the Psi Corps in such a way as to *prevent* them from becoming a deus ex
machina all the time. This is what's always bothered me about the way
"empaths" are treated on ST; it's a terrible invasion of privacy. The Psi
Corps has strict rules about who can and can't be scanned, and under what
conditions. In "Purple," she couldn't just go scan Trakis; she had to be
hired, had to be already engaged in a business capacity, and had to find
it *only* in surface thoughts, no deliberate poking. And this is the ONLY
-- repeat, the ONLY -- time this is done in the entire season, aside from
the accidental run-in with Londo in the pilot episode.
We'll get deeper into the rules and regs of the Psi Corps as we go,
further establishing that there's a lot they're expressly forbidden from
doing by law.