New report on gas prices says B.C. drivers still paying more than is justified.
The fullstop in OP's example led me into thinking something was indeed missing.
Only after searching further did I notice that that example (minus the fullstop) is the title of a video.
Titles are commonly not full sentences. For that, we can do without, for example, what:
New report on gas prices says B.C. drivers still paying more than (what) is justified
If we want to form a complete sentence, we could either insert are or reconstruct the sentence.
New report on gas prices says B.C. drivers [are] still paying more than (what) is justified.