You could try to equate it with theft, but you'd make a poor argument. It's typical for licensing and other contracts to include provisions for minimums (in either direction, depending on who the bigger company is). Spotify isn't paying for an inventory of 1000 plays to give to its users, it has licensed the songs for unlimited (I assume) use within the platform from the publihers. Artist streaming payouts are a small line item in the contract.

> manufacturer not being paid for the first 1,000 candy bars sold at a grocery store

This happens, in any case. People set up deals with grocery stores for 100k units. The store changes its mind. You're left with a huge inventory to either sell to them at a discount or find a new buyer.