Absolutely true.
My daughter is studying opera at the Jacobs School, and has probably another 5 years or so of training before she could be considered a viable candidate for a lead role in a major opera company (though she has the lead role in their fall opera this year, ahead of a number of grad students).
Meanwhile, she can walk into just about any other type of vocal audition and score straight 10/10s. I music direct with a couple of community theater groups, and I can guarantee you that any trained opera singer will blow away any other sort of vocal setting in technique, diction, presentation, power, and sight reading.
There's a lot more to it than that. "Classical" performers are selected by highly trained, skilled professionals on the basis of their technical skill and ability BEFORE they are allowed to perform or record; opera is the highest level of vocal performance within the classical spaces, so it is reserved for the absolutely highest-skill performers. Other genres focus on other aspects, like songwriting, look, and sometimes just acceptance by a lowest-common-denominator audience. Sure, there are operatic pieces that can be sung by lesser-trained vocalists, but they will never pass the audition to get themselves on an opera stage.
Put another way, CC Deville and Ace Frehley sold a lot of records playing simple guitar parts, but there's no way either would ever take a gig from Chris Parkening, no matter how well they might be able to play a specific piece; they simply aren't qualified for the gig.
Oh, and BTW, most operatic performers still work without mics. Broadway performers use headsets, but not opera.