Plenty of costs don’t depend on how much usage there is. If a tree falls and takes out a power line it cosrs the same whether that line was being used at 1% capacity or 100%

How exactly is it hashed? There aren’t that many possible phone numbers, so it might be viable to just try every valid number until you find one that matches

Blaming Spotify for this is like blaming the company that made your TV for showing you ads that are part of the broadcast. Unless Spotify makes the specific podcast you’re listening to, they’re just playing you the content someone else made, including the ads they included in that content.