What are "subwoofer cables" and how are they different?

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What are "subwoofer cables" and how are they different?
Subwoofer cables in both XLR and RCA are sold by audioquest in multiple tiers and nordost makes one in green. Wireworld makes some in their lowest tiers and only RCA. Shunyata doesn't offer one.

When my home theater system was installed my salesman hooked up my system for free, and brought plenty of mid quality cables with him. I have a giant bin of low to low-mid quality cables and he didn't have a "subwoofer cable" which made him passive aggressive when I offered my old RCA cables to use. He said they're different with solid core or something I didn't understand. We ended up finding a subwoofer rca cable in my bin, but my sales guy was frustrated it wasn't a better one.

I've learned that cables matter, but if a subwoofer cable mattered wouldn't Shunyata make them?