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Why is it that at some companies blue-collar workers have better pay than white-collar workers?
Literal
Why, company [depending on-によって], blue-collar [genitive-の] people [genitive-の] side [subject-が], white-collar [genitive-の] people [than-より] salary [subject-が] good [question-ですか]?
An economics/labor question using the polite comparative pattern ~の方が~より ('A is more X than B'). 会社によって ('depending on the company') uses によって in its 'varies depending on' sense — the comparison is not universal but situational. Note that 給料がいい ('salary is good,' i.e., 'pays well') is a casual/natural collocation — 高い ('high') would also work but いい is more conversational. The sentence-structure is a full comparative question with the polite ですか ending — a researcher's or curious speaker's framing.